PresentationonReal Time Operating Systems

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电脑使用指南英语作文

电脑使用指南英语作文英文回答：Computer User Guide.Congratulations on purchasing your new computer! This guide will provide you with all the information you need to get started using your computer.Getting Started.1. Unpack your computer. Carefully remove your computer from the box and remove all packaging materials.2. Connect your computer to a power source. Plug the power cord into an electrical outlet.3. Turn on your computer. Press the power button on the front of the computer.4. Set up your operating system. Follow the on-screen instructions to set up your operating system.5. Create a user account. Create a user account so that you can log in to your computer and access your files.6. Install software. Install any software that you need to use on your computer.Using Your Computer.Using the desktop. The desktop is the main screen of your computer. It contains icons that represent your programs, files, and folders.Opening programs. To open a program, double-click on its icon.Working with files. To open a file, double-click onits icon. To save a file, click on the "File" menu and select "Save."Browsing the internet. To browse the internet, open a web browser such as Chrome or Firefox.Sending email. To send email, open an email program such as Outlook or Gmail.Troubleshooting.My computer won't turn on. Check that the power cord is plugged in and that the power switch is turned on.My computer is running slowly. Close any unnecessary programs and restart your computer.I can't connect to the internet. Check that your computer is connected to a network and that your network is working.I'm getting an error message. Look up the error message in the help file or on the manufacturer's website.Safety Precautions.Do not place your computer in a humid environment. This can damage the computer's components.Do not spill liquids on your computer. This can short-circuit the computer and damage its components.Do not drop your computer. This can damage the computer's components.Unplug your computer from the power source when you are not using it. This will help to prevent electrical shocks and fires.中文回答：电脑使用指南。

产品演示英语作文

产品演示英语作文Title: Product Demonstration: Unveiling Innovation in English。

Introduction:Product demonstrations serve as pivotal moments in showcasing innovation and functionality. Whether presenting a new gadget, software, or service, the effectiveness of the demonstration can significantly impact audience engagement and perception. In this essay, we delve into the art of delivering compelling product demonstrations in English, exploring strategies to captivate audiences and effectively communicate the value proposition of the product.Captivating Opening:To capture the audience's attention from the outset,it's essential to begin with a captivating opening thatpiques their curiosity. Consider starting with a thought-provoking question, a startling statistic, or a compelling anecdote related to the problem your product aims to solve. This sets the stage for the demonstration and primes the audience for what's to come.Engaging Content:The heart of a successful product demonstration lies in its content. Break down the features and benefits of the product into digestible segments, ensuring clarity and relevance throughout. Utilize visuals, such as slides or videos, to supplement your verbal explanations and provide concrete examples of how the product functions in real-world scenarios. Remember to tailor the content to the specific needs and interests of your audience, highlighting key selling points that resonate with them.Interactive Elements:To foster active engagement and participation, incorporate interactive elements into your demonstration.This could involve conducting live polls, inviting audience members to ask questions, or facilitating hands-on experiences with the product if feasible. By involving the audience directly, you create a sense of involvement and investment in the product, increasing their likelihood of retaining information and forming a positive impression.Clear Communication:Effective communication is paramount in ensuring that your message resonates with the audience. Speak clearly and confidently, avoiding jargon or technical language that may alienate those unfamiliar with the product domain. Instead, use simple and concise language to convey complex concepts, ensuring that everyone in the audience can follow along and understand the value proposition of the product.Demonstration Flow:Maintaining a smooth and cohesive flow throughout the demonstration is essential for keeping the audience engaged. Structure your presentation in a logical sequence, startingwith an introduction to the product, followed by a detailed overview of its features and benefits, and concluding with a call to action or next steps for interested parties. Avoid jumping between topics haphazardly, as this can disrupt the flow and confuse the audience.Effective Use of Visual Aids:Visual aids, such as slides or product demos, can significantly enhance the clarity and impact of your presentation. However, it's important to use them judiciously and ensure they complement rather than overshadow your verbal explanations. Keep slides uncluttered and visually appealing, using images, graphs, and charts to reinforce key points and provide visual context for complex ideas.Handling Q&A:The question and answer session following the demonstration offers an opportunity to address anylingering doubts or concerns the audience may have.Encourage participants to ask questions openly and provide thoughtful, well-informed responses that demonstrate your expertise and confidence in the product. If you're unsure about a particular query, don't hesitate to acknowledge it and offer to follow up with more information after the demonstration.Conclusion:In conclusion, delivering a compelling product demonstration in English requires a combination of preparation, engagement, and effective communication. By captivating your audience with a compelling opening, delivering engaging content, incorporating interactive elements, and maintaining clear communication throughout, you can effectively showcase the value proposition of your product and leave a lasting impression on your audience.。

(完整版)操作系统课程英文词汇

操作系统课程英文词汇_1.操作系统Operating System2.计算机Computer3.内核映像Core Image4.超级用户Super-user5.进程Process6.线程Threads7.输入/输出I/O (Input/Output)8.多处理器操作系统Multiprocessor OperatingSystems9.个人计算机操作系统Personal ComputerOperating Systems10.实时操作系统Real-Time Operating Systems11.处理机Processor12.内存Memory13.进程间通信Interprocess Communication14.输入/输出设备I/O Devices15.总线Buses16.死锁Deadlock17.内存管理Memory Management18.输入/输出Input/Output19.文件Files20.文件系统File System21.文件扩展名File Extension22.顺序存取Sequential Access23.随机存取文件Random Access File24.文件属性Attribute25.绝对路径Absolute Path26.相对路径Relative Path27.安全Security28.系统调用System Calls29.操作系统结构Operating System Structure30.层次系统Layered Systems31.虚拟机Virtual Machines32.客户/服务器模式Client/Server Mode33.线程Threads34.调度激活Scheduler Activations35.信号量Semaphores36.二进制信号量Binary Semaphore37.互斥Mutexes38.互斥Mutual Exclusion39.优先级Priority40.监控程序Monitors41.管程Monitor 42.管道Pipe43.临界区Critical Section44.忙等待Busy Waiting45.原子操作Atomic Action46.同步Synchronization47.调度算法Scheduling Algorithm48.剥夺调度Preemptive Scheduling49.非剥夺调度Nonpreemptive Scheduling50.硬实时Hard Real Time51.软实时Soft Real Time52.调度机制Scheduling Mechanism53.调度策略Scheduling Policy54.任务Task55.设备驱动程序Device Driver56.内存管理器Memory Manager57.引导程序Bootstrap58.时间片Quantum59.进程切换Process Switch60.上下文切换Context Switch61.重定位Relocation62.位示图Bitmaps63.链表Linked List64.虚拟存储器Virtual Memory65.页Page66.页面Page Frame67.页面Page Frame68.修改Modify69.访问Reference70.联想存储器Associative Memory71.命中率Hit Ration72.消息传递Message Passing73.目录Directory74.设备文件Special File75.块设备文件Block Special File76.字符设备文件Character Special File77.字符设备Character Device78.块设备Block Device79.纠错码Error-Correcting Code80.直接内存存取Direct Memory Access81.统一命名法Uniform Naming82.可剥夺资源Preemptable Resource83.不可剥夺资源Nonpreemptable Resource84.先来先服务First-Come First-Served85.最短寻道算法Shortest Seek First86.电梯算法Elevator Algorithm87.引导参数Boot Parameter88.时钟滴答Clock Tick89.内核调用Kernel Call90.客户进程Client Process91.服务器进程Server Process92.条件变量Condition Variable93.信箱Mailbox94.应答Acknowledgement95.饥饿Starvation96.空指针Null Pointer97.规范模式Canonical Mode98.非规范模式Uncanonical Mode99.代码页Code Page100.虚拟控制台Virtual Console101.高速缓存Cache102.基地址Base103.界限Limit104.交换Swapping105.内存压缩Memory Compaction 106.最佳适配Best Fit107.最坏适配Worst Fit108.虚地址Virtual Address109.页表Page Table110.缺页故障Page Fault111.最近未使用Not Recently Used 112.最久未使用Least Recently Used 113.工作集Working Set114.请调Demand Paging115.预调Prepaging116.访问的局部性Locality of Reference 117.颠簸Thrashing118.内零头Internal Fragmentation 119.外零头External Fragmentation 120.共享正文Shared Text121.增量转储Incremental Dump 122.权限表Capability List123.访问控制表Access Control List。

CoDeSys SP RTE_E使用说明

Documentation for OEMs: CoDeSys SP RTE Realtime Runtime System for Windows NT/2000/XP
Document Version 2.2
tech_doc_e.doc / V1.1
3S - Smart Software Solutions GmbH CoDeSys SP RTE_E.doc
1.1
What does "real time extension" mean?
A real time system is characterized by predictable (deterministic) time behaviour. If for example a real time system is given the task of executing specific routines (through configuration) within a predetermined time pattern this will happen within predetermined temporal ranges of tolerance. If this is not the case it is regarded as a failure of the whole system. If this is applied to a controller such as CoDeSys this means that a task is called within predetermined (known) ranges of tolerance. Figures drawn from past experience have shown that these ranges are not adhered to by Windows NT, which means that NT is not a genuine realtime operating system. Yet the hardware in a PC is made in such a way that it is possible to create a reliable task scheduling by means of software. The real time extension of Windows NT is an NT driver which installs an Interrupt-Service-Routine which is called-up cyclically by the timertick of the PC’s hardware. This routine now takes over the job of calling-up defined tasks from CoDeSys and/or of authorizing the continued or renewed execution of the operating system.

现代操作系统(第三版)答案

MODERNOPERATINGSYSTEMSTHIRD EDITION PROBLEM SOLUTIONSANDREW S.TANENBAUMVrije UniversiteitAmsterdam,The NetherlandsPRENTICE HALLUPPER SADDLE RIVER,NJ07458Copyright Pearson Education,Inc.2008SOLUTIONS TO CHAPTER1PROBLEMS1.Multiprogramming is the rapid switching of the CPU between multiple proc-esses in memory.It is commonly used to keep the CPU busy while one or more processes are doing I/O.2.Input spooling is the technique of reading in jobs,for example,from cards,onto the disk,so that when the currently executing processes areﬁnished, there will be work waiting for the CPU.Output spooling consists ofﬁrst copying printableﬁles to disk before printing them,rather than printing di-rectly as the output is generated.Input spooling on a personal computer is not very likely,but output spooling is.3.The prime reason for multiprogramming is to give the CPU something to dowhile waiting for I/O to complete.If there is no DMA,the CPU is fully occu-pied doing I/O,so there is nothing to be gained(at least in terms of CPU utili-zation)by multiprogramming.No matter how much I/O a program does,the CPU will be100%busy.This of course assumes the major delay is the wait while data are copied.A CPU could do other work if the I/O were slow for other reasons(arriving on a serial line,for instance).4.It is still alive.For example,Intel makes Pentium I,II,and III,and4CPUswith a variety of different properties including speed and power consumption.All of these machines are architecturally compatible.They differ only in price and performance,which is the essence of the family idea.5.A25×80character monochrome text screen requires a2000-byte buffer.The1024×768pixel24-bit color bitmap requires2,359,296bytes.In1980these two options would have cost$10and$11,520,respectively.For current prices,check on how much RAM currently costs,probably less than$1/MB.6.Consider fairness and real time.Fairness requires that each process be allo-cated its resources in a fair way,with no process getting more than its fair share.On the other hand,real time requires that resources be allocated based on the times when different processes must complete their execution.A real-time process may get a disproportionate share of the resources.7.Choices(a),(c),and(d)should be restricted to kernel mode.8.It may take20,25or30msec to complete the execution of these programsdepending on how the operating system schedules them.If P0and P1are scheduled on the same CPU and P2is scheduled on the other CPU,it will take20mses.If P0and P2are scheduled on the same CPU and P1is scheduled on the other CPU,it will take25msec.If P1and P2are scheduled on the same CPU and P0is scheduled on the other CPU,it will take30msec.If all three are on the same CPU,it will take35msec.2PROBLEM SOLUTIONS FOR CHAPTER19.Every nanosecond one instruction emerges from the pipeline.This means themachine is executing1billion instructions per second.It does not matter at all how many stages the pipeline has.A10-stage pipeline with1nsec per stage would also execute1billion instructions per second.All that matters is how often aﬁnished instruction pops out the end of the pipeline.10.Average access time=0.95×2nsec(word is cache)+0.05×0.99×10nsec(word is in RAM,but not in cache)+0.05×0.01×10,000,000nsec(word on disk only)=5002.395nsec=5.002395μsec11.The manuscript contains80×50×700=2.8million characters.This is,ofcourse,impossible toﬁt into the registers of any currently available CPU and is too big for a1-MB cache,but if such hardware were available,the manuscript could be scanned in2.8msec from the registers or5.8msec from the cache.There are approximately27001024-byte blocks of data,so scan-ning from the disk would require about27seconds,and from tape2minutes7 seconds.Of course,these times are just to read the data.Processing and rewriting the data would increase the time.12.Maybe.If the caller gets control back and immediately overwrites the data,when the writeﬁnally occurs,the wrong data will be written.However,if the driverﬁrst copies the data to a private buffer before returning,then the caller can be allowed to continue immediately.Another possibility is to allow the caller to continue and give it a signal when the buffer may be reused,but this is tricky and error prone.13.A trap instruction switches the execution mode of a CPU from the user modeto the kernel mode.This instruction allows a user program to invoke func-tions in the operating system kernel.14.A trap is caused by the program and is synchronous with it.If the program isrun again and again,the trap will always occur at exactly the same position in the instruction stream.An interrupt is caused by an external event and its timing is not reproducible.15.The process table is needed to store the state of a process that is currentlysuspended,either ready or blocked.It is not needed in a single process sys-tem because the single process is never suspended.16.Mounting aﬁle system makes anyﬁles already in the mount point directoryinaccessible,so mount points are normally empty.However,a system admin-istrator might want to copy some of the most importantﬁles normally located in the mounted directory to the mount point so they could be found in their normal path in an emergency when the mounted device was being repaired.PROBLEM SOLUTIONS FOR CHAPTER13 17.A system call allows a user process to access and execute operating systemfunctions inside the er programs use system calls to invoke operat-ing system services.18.Fork can fail if there are no free slots left in the process table(and possibly ifthere is no memory or swap space left).Exec can fail if theﬁle name given does not exist or is not a valid executableﬁle.Unlink can fail if theﬁle to be unlinked does not exist or the calling process does not have the authority to unlink it.19.If the call fails,for example because fd is incorrect,it can return−1.It canalso fail because the disk is full and it is not possible to write the number of bytes requested.On a correct termination,it always returns nbytes.20.It contains the bytes:1,5,9,2.21.Time to retrieve theﬁle=1*50ms(Time to move the arm over track#50)+5ms(Time for theﬁrst sector to rotate under the head)+10/100*1000ms(Read10MB)=155ms22.Block specialﬁles consist of numbered blocks,each of which can be read orwritten independently of all the other ones.It is possible to seek to any block and start reading or writing.This is not possible with character specialﬁles.23.System calls do not really have names,other than in a documentation sense.When the library procedure read traps to the kernel,it puts the number of the system call in a register or on the stack.This number is used to index into a table.There is really no name used anywhere.On the other hand,the name of the library procedure is very important,since that is what appears in the program.24.Yes it can,especially if the kernel is a message-passing system.25.As far as program logic is concerned it does not matter whether a call to a li-brary procedure results in a system call.But if performance is an issue,if a task can be accomplished without a system call the program will run faster.Every system call involves overhead time in switching from the user context to the kernel context.Furthermore,on a multiuser system the operating sys-tem may schedule another process to run when a system call completes, further slowing the progress in real time of a calling process.26.Several UNIX calls have no counterpart in the Win32API:Link:a Win32program cannot refer to aﬁle by an alternative name or see it in more than one directory.Also,attempting to create a link is a convenient way to test for and create a lock on aﬁle.4PROBLEM SOLUTIONS FOR CHAPTER1Mount and umount:a Windows program cannot make assumptions about standard path names because on systems with multiple disk drives the drive name part of the path may be different.Chmod:Windows uses access control listsKill:Windows programmers cannot kill a misbehaving program that is not cooperating.27.Every system architecture has its own set of instructions that it can execute.Thus a Pentium cannot execute SPARC programs and a SPARC cannot exe-cute Pentium programs.Also,different architectures differ in bus architecture used(such as VME,ISA,PCI,MCA,SBus,...)as well as the word size of the CPU(usually32or64bit).Because of these differences in hardware,it is not feasible to build an operating system that is completely portable.A highly portable operating system will consist of two high-level layers---a machine-dependent layer and a machine independent layer.The machine-dependent layer addresses the specifics of the hardware,and must be implemented sepa-rately for every architecture.This layer provides a uniform interface on which the machine-independent layer is built.The machine-independent layer has to be implemented only once.To be highly portable,the size of the machine-dependent layer must be kept as small as possible.28.Separation of policy and mechanism allows OS designers to implement asmall number of basic primitives in the kernel.These primitives are sim-pliﬁed,because they are not dependent of any specific policy.They can then be used to implement more complex mechanisms and policies at the user level.29.The conversions are straightforward:(a)A micro year is10−6×365×24×3600=31.536sec.(b)1000meters or1km.(c)There are240bytes,which is1,099,511,627,776bytes.(d)It is6×1024kg.SOLUTIONS TO CHAPTER2PROBLEMS1.The transition from blocked to running is conceivable.Suppose that a processis blocked on I/O and the I/Oﬁnishes.If the CPU is otherwise idle,the proc-ess could go directly from blocked to running.The other missing transition, from ready to blocked,is impossible.A ready process cannot do I/O or any-thing else that might block it.Only a running process can block.PROBLEM SOLUTIONS FOR CHAPTER25 2.You could have a register containing a pointer to the current process tableentry.When I/O completed,the CPU would store the current machine state in the current process table entry.Then it would go to the interrupt vector for the interrupting device and fetch a pointer to another process table entry(the ser-vice procedure).This process would then be started up.3.Generally,high-level languages do not allow the kind of access to CPU hard-ware that is required.For instance,an interrupt handler may be required to enable and disable the interrupt servicing a particular device,or to manipulate data within a process’stack area.Also,interrupt service routines must exe-cute as rapidly as possible.4.There are several reasons for using a separate stack for the kernel.Two ofthem are as follows.First,you do not want the operating system to crash be-cause a poorly written user program does not allow for enough stack space.Second,if the kernel leaves stack data in a user program’s memory space upon return from a system call,a malicious user might be able to use this data toﬁnd out information about other processes.5.If each job has50%I/O wait,then it will take20minutes to complete in theabsence of competition.If run sequentially,the second one willﬁnish40 minutes after theﬁrst one starts.With two jobs,the approximate CPU utiliza-tion is1−0.52.Thus each one gets0.375CPU minute per minute of real time.To accumulate10minutes of CPU time,a job must run for10/0.375 minutes,or about26.67minutes.Thus running sequentially the jobsﬁnish after40minutes,but running in parallel theyﬁnish after26.67minutes.6.It would be difﬁcult,if not impossible,to keep theﬁle system consistent.Sup-pose that a client process sends a request to server process1to update aﬁle.This process updates the cache entry in its memory.Shortly thereafter,anoth-er client process sends a request to server2to read thatﬁle.Unfortunately,if theﬁle is also cached there,server2,in its innocence,will return obsolete data.If theﬁrst process writes theﬁle through to the disk after caching it, and server2checks the disk on every read to see if its cached copy is up-to-date,the system can be made to work,but it is precisely all these disk ac-cesses that the caching system is trying to avoid.7.No.If a single-threaded process is blocked on the keyboard,it cannot fork.8.A worker thread will block when it has to read a Web page from the disk.Ifuser-level threads are being used,this action will block the entire process, destroying the value of multithreading.Thus it is essential that kernel threads are used to permit some threads to block without affecting the others.9.Yes.If the server is entirely CPU bound,there is no need to have multiplethreads.It just adds unnecessary complexity.As an example,consider a tele-phone directory assistance number(like555-1212)for an area with1million6PROBLEM SOLUTIONS FOR CHAPTER2people.If each(name,telephone number)record is,say,64characters,the entire database takes64megabytes,and can easily be kept in the server’s memory to provide fast lookup.10.When a thread is stopped,it has values in the registers.They must be saved,just as when the process is stopped the registers must be saved.Multipro-gramming threads is no different than multiprogramming processes,so each thread needs its own register save area.11.Threads in a process cooperate.They are not hostile to one another.If yield-ing is needed for the good of the application,then a thread will yield.After all,it is usually the same programmer who writes the code for all of them. er-level threads cannot be preempted by the clock unless the whole proc-ess’quantum has been used up.Kernel-level threads can be preempted indivi-dually.In the latter case,if a thread runs too long,the clock will interrupt the current process and thus the current thread.The kernel is free to pick a dif-ferent thread from the same process to run next if it so desires.13.In the single-threaded case,the cache hits take15msec and cache misses take90msec.The weighted average is2/3×15+1/3×90.Thus the mean re-quest takes40msec and the server can do25per second.For a multithreaded server,all the waiting for the disk is overlapped,so every request takes15 msec,and the server can handle662/3requests per second.14.The biggest advantage is the efﬁciency.No traps to the kernel are needed toswitch threads.The biggest disadvantage is that if one thread blocks,the en-tire process blocks.15.Yes,it can be done.After each call to pthread create,the main programcould do a pthread join to wait until the thread just created has exited before creating the next thread.16.The pointers are really necessary because the size of the global variable isunknown.It could be anything from a character to an array ofﬂoating-point numbers.If the value were stored,one would have to give the size to create global,which is all right,but what type should the second parameter of set global be,and what type should the value of read global be?17.It could happen that the runtime system is precisely at the point of blocking orunblocking a thread,and is busy manipulating the scheduling queues.This would be a very inopportune moment for the clock interrupt handler to begin inspecting those queues to see if it was time to do thread switching,since they might be in an inconsistent state.One solution is to set aﬂag when the run-time system is entered.The clock handler would see this and set its ownﬂag, then return.When the runtime systemﬁnished,it would check the clockﬂag, see that a clock interrupt occurred,and now run the clock handler.PROBLEM SOLUTIONS FOR CHAPTER27 18.Yes it is possible,but inefﬁcient.A thread wanting to do a system callﬁrstsets an alarm timer,then does the call.If the call blocks,the timer returns control to the threads package.Of course,most of the time the call will not block,and the timer has to be cleared.Thus each system call that might block has to be executed as three system calls.If timers go off prematurely,all kinds of problems can develop.This is not an attractive way to build a threads package.19.The priority inversion problem occurs when a low-priority process is in itscritical region and suddenly a high-priority process becomes ready and is scheduled.If it uses busy waiting,it will run forever.With user-level threads,it cannot happen that a low-priority thread is suddenly preempted to allow a high-priority thread run.There is no preemption.With kernel-level threads this problem can arise.20.With round-robin scheduling it works.Sooner or later L will run,and eventu-ally it will leave its critical region.The point is,with priority scheduling,L never gets to run at all;with round robin,it gets a normal time slice periodi-cally,so it has the chance to leave its critical region.21.Each thread calls procedures on its own,so it must have its own stack for thelocal variables,return addresses,and so on.This is equally true for user-level threads as for kernel-level threads.22.Yes.The simulated computer could be multiprogrammed.For example,while process A is running,it reads out some shared variable.Then a simula-ted clock tick happens and process B runs.It also reads out the same vari-able.Then it adds1to the variable.When process A runs,if it also adds one to the variable,we have a race condition.23.Yes,it still works,but it still is busy waiting,of course.24.It certainly works with preemptive scheduling.In fact,it was designed forthat case.When scheduling is nonpreemptive,it might fail.Consider the case in which turn is initially0but process1runsﬁrst.It will just loop forever and never release the CPU.25.To do a semaphore operation,the operating systemﬁrst disables interrupts.Then it reads the value of the semaphore.If it is doing a down and the sema-phore is equal to zero,it puts the calling process on a list of blocked processes associated with the semaphore.If it is doing an up,it must check to see if any processes are blocked on the semaphore.If one or more processes are block-ed,one of them is removed from the list of blocked processes and made run-nable.When all these operations have been completed,interrupts can be enabled again.8PROBLEM SOLUTIONS FOR CHAPTER226.Associated with each counting semaphore are two binary semaphores,M,used for mutual exclusion,and B,used for blocking.Also associated with each counting semaphore is a counter that holds the number of up s minus the number of down s,and a list of processes blocked on that semaphore.To im-plement down,a processﬁrst gains exclusive access to the semaphores, counter,and list by doing a down on M.It then decrements the counter.If it is zero or more,it just does an up on M and exits.If M is negative,the proc-ess is put on the list of blocked processes.Then an up is done on M and a down is done on B to block the process.To implement up,ﬁrst M is down ed to get mutual exclusion,and then the counter is incremented.If it is more than zero,no one was blocked,so all that needs to be done is to up M.If, however,the counter is now negative or zero,some process must be removed from the list.Finally,an up is done on B and M in that order.27.If the program operates in phases and neither process may enter the nextphase until both areﬁnished with the current phase,it makes perfect sense to use a barrier.28.With kernel threads,a thread can block on a semaphore and the kernel canrun some other thread in the same process.Consequently,there is no problem using semaphores.With user-level threads,when one thread blocks on a semaphore,the kernel thinks the entire process is blocked and does not run it ever again.Consequently,the process fails.29.It is very expensive to implement.Each time any variable that appears in apredicate on which some process is waiting changes,the run-time system must re-evaluate the predicate to see if the process can be unblocked.With the Hoare and Brinch Hansen monitors,processes can only be awakened on a signal primitive.30.The employees communicate by passing messages:orders,food,and bags inthis case.In UNIX terms,the four processes are connected by pipes.31.It does not lead to race conditions(nothing is ever lost),but it is effectivelybusy waiting.32.It will take nT sec.33.In simple cases it may be possible to determine whether I/O will be limitingby looking at source code.For instance a program that reads all its inputﬁles into buffers at the start will probably not be I/O bound,but a problem that reads and writes incrementally to a number of differentﬁles(such as a compi-ler)is likely to be I/O bound.If the operating system provides a facility such as the UNIX ps command that can tell you the amount of CPU time used by a program,you can compare this with the total time to complete execution of the program.This is,of course,most meaningful on a system where you are the only user.34.For multiple processes in a pipeline,the common parent could pass to the op-erating system information about the ﬂow of data.With this information the OS could,for instance,determine which process could supply output to a process blocking on a call for input.35.The CPU efﬁciency is the useful CPU time divided by the total CPU time.When Q ≥T ,the basic cycle is for the process to run for T and undergo a process switch for S .Thus (a)and (b)have an efﬁciency of T /(S +T ).When the quantum is shorter than T ,each run of T will require T /Q process switches,wasting a time ST /Q .The efﬁciency here is thenT +ST /QT which reduces to Q /(Q +S ),which is the answer to (c).For (d),we just sub-stitute Q for S and ﬁnd that the efﬁciency is 50%.Finally,for (e),as Q →0the efﬁciency goes to 0.36.Shortest job ﬁrst is the way to minimize average response time.0<X ≤3:X ,3,5,6,9.3<X ≤5:3,X ,5,6,9.5<X ≤6:3,5,X ,6,9.6<X ≤9:3,5,6,X ,9.X >9:3,5,6,9,X.37.For round robin,during the ﬁrst 10minutes each job gets 1/5of the CPU.Atthe end of 10minutes,C ﬁnishes.During the next 8minutes,each job gets 1/4of the CPU,after which time D ﬁnishes.Then each of the three remaining jobs gets 1/3of the CPU for 6minutes,until B ﬁnishes,and so on.The ﬁn-ishing times for the ﬁve jobs are 10,18,24,28,and 30,for an average of 22minutes.For priority scheduling,B is run ﬁrst.After 6minutes it is ﬁnished.The other jobs ﬁnish at 14,24,26,and 30,for an average of 18.8minutes.If the jobs run in the order A through E ,they ﬁnish at 10,16,18,22,and 30,for an average of 19.2minutes.Finally,shortest job ﬁrst yields ﬁnishing times of 2,6,12,20,and 30,for an average of 14minutes.38.The ﬁrst time it gets 1quantum.On succeeding runs it gets 2,4,8,and 15,soit must be swapped in 5times.39.A check could be made to see if the program was expecting input and didanything with it.A program that was not expecting input and did not process it would not get any special priority boost.40.The sequence of predictions is 40,30,35,and now 25.41.The fraction of the CPU used is35/50+20/100+10/200+x/250.To beschedulable,this must be less than1.Thus x must be less than12.5msec. 42.Two-level scheduling is needed when memory is too small to hold all theready processes.Some set of them is put into memory,and a choice is made from that set.From time to time,the set of in-core processes is adjusted.This algorithm is easy to implement and reasonably efﬁcient,certainly a lot better than,say,round robin without regard to whether a process was in memory or not.43.Each voice call runs200times/second and uses up1msec per burst,so eachvoice call needs200msec per second or400msec for the two of them.The video runs25times a second and uses up20msec each time,for a total of 500msec per second.Together they consume900msec per second,so there is time left over and the system is schedulable.44.The kernel could schedule processes by any means it wishes,but within eachprocess it runs threads strictly in priority order.By letting the user process set the priority of its own threads,the user controls the policy but the kernel handles the mechanism.45.The change would mean that after a philosopher stopped eating,neither of hisneighbors could be chosen next.In fact,they would never be chosen.Sup-pose that philosopher2ﬁnished eating.He would run test for philosophers1 and3,and neither would be started,even though both were hungry and both forks were available.Similarly,if philosopher4ﬁnished eating,philosopher3 would not be started.Nothing would start him.46.If a philosopher blocks,neighbors can later see that she is hungry by checkinghis state,in test,so he can be awakened when the forks are available.47.Variation1:readers have priority.No writer may start when a reader is ac-tive.When a new reader appears,it may start immediately unless a writer is currently active.When a writerﬁnishes,if readers are waiting,they are all started,regardless of the presence of waiting writers.Variation2:Writers have priority.No reader may start when a writer is waiting.When the last ac-tive processﬁnishes,a writer is started,if there is one;otherwise,all the readers(if any)are started.Variation3:symmetric version.When a reader is active,new readers may start immediately.When a writerﬁnishes,a new writer has priority,if one is waiting.In other words,once we have started reading,we keep reading until there are no readers left.Similarly,once we have started writing,all pending writers are allowed to run.48.A possible shell script might beif[!–f numbers];then echo0>numbers;ﬁcount=0while(test$count!=200)docount=‘expr$count+1‘n=‘tail–1numbers‘expr$n+1>>numbersdoneRun the script twice simultaneously,by starting it once in the background (using&)and again in the foreground.Then examine theﬁle numbers.It will probably start out looking like an orderly list of numbers,but at some point it will lose its orderliness,due to the race condition created by running two cop-ies of the script.The race can be avoided by having each copy of the script test for and set a lock on theﬁle before entering the critical area,and unlock-ing it upon leaving the critical area.This can be done like this:if ln numbers numbers.lockthenn=‘tail–1numbers‘expr$n+1>>numbersrm numbers.lockﬁThis version will just skip a turn when theﬁle is inaccessible,variant solu-tions could put the process to sleep,do busy waiting,or count only loops in which the operation is successful.SOLUTIONS TO CHAPTER3PROBLEMS1.It is an accident.The base register is16,384because the program happened tobe loaded at address16,384.It could have been loaded anywhere.The limit register is16,384because the program contains16,384bytes.It could have been any length.That the load address happens to exactly match the program length is pure coincidence.2.Almost the entire memory has to be copied,which requires each word to beread and then rewritten at a different location.Reading4bytes takes10nsec, so reading1byte takes2.5nsec and writing it takes another2.5nsec,for a total of5nsec per byte compacted.This is a rate of200,000,000bytes/sec.To copy128MB(227bytes,which is about1.34×108bytes),the computer needs227/200,000,000sec,which is about671msec.This number is slightly pessimistic because if the initial hole at the bottom of memory is k bytes, those k bytes do not need to be copied.However,if there are many holes andmany data segments,the holes will be small,so k will be small and the error in the calculation will also be small.3.The bitmap needs1bit per allocation unit.With227/n allocation units,this is224/n bytes.The linked list has227/216or211nodes,each of8bytes,for a total of214bytes.For small n,the linked list is better.For large n,the bitmap is better.The crossover point can be calculated by equating these two formu-las and solving for n.The result is1KB.For n smaller than1KB,a linked list is better.For n larger than1KB,a bitmap is better.Of course,the assumption of segments and holes alternating every64KB is very unrealistic.Also,we need n<=64KB if the segments and holes are64KB.4.Firstﬁt takes20KB,10KB,18KB.Bestﬁt takes12KB,10KB,and9KB.Worstﬁt takes20KB,18KB,and15KB.Nextﬁt takes20KB,18KB,and9 KB.5.For a4-KB page size the(page,offset)pairs are(4,3616),(8,0),and(14,2656).For an8-KB page size they are(2,3616),(4,0),and(7,2656).6.They built an MMU and inserted it between the8086and the bus.Thus all8086physical addresses went into the MMU as virtual addresses.The MMU then mapped them onto physical addresses,which went to the bus.7.(a)M has to be at least4,096to ensure a TLB miss for every access to an ele-ment of X.Since N only affects how many times X is accessed,any value of N will do.(b)M should still be atleast4,096to ensure a TLB miss for every access to anelement of X.But now N should be greater than64K to thrash the TLB, that is,X should exceed256KB.8.The total virtual address space for all the processes combined is nv,so thismuch storage is needed for pages.However,an amount r can be in RAM,so the amount of disk storage required is only nv−r.This amount is far more than is ever needed in practice because rarely will there be n processes ac-tually running and even more rarely will all of them need the maximum al-lowed virtual memory.9.The page table contains232/213entries,which is524,288.Loading the pagetable takes52msec.If a process gets100msec,this consists of52msec for loading the page table and48msec for running.Thus52%of the time is spent loading page tables.10.(a)We need one entry for each page,or224=16×1024×1024entries,sincethere are36=48−12bits in the page numberﬁeld.。

虚拟现实英文讲课文档

Three-dimensional animation
Supports stereoscopic display and 3D stereo, three-dimensional reality.
Does not support
No time limit, can show a true and detailed, and you can export files in virtual reality animated video based on the same data can be used for the production of multi-mode body and publicity, cost-effective.
Animation by the time limit, can not be detailed display, low price.
In real-time three-dimensional environment, adjustment support programs, assessment, management, information inquiry and other functions, suitable for larger complex project planning, design, bidding, approval, management and other needs, but also has a more realistic and intuitive multimedia presentation capabilities.
• Virtual reality technology is essentially a highly realistic simulation of human vision in real life. Hearing. Action and other acts of interactive technology.

操作系统功能体验报告英文

操作系统功能体验报告英文IntroductionIn this report, we will review the functionality and features of an operating system. An operating system is a software that manages computer hardware and software resources, providing common services for computer programs. We will evaluate the operating system based on its performance, user interface, security, and compatibility.PerformanceOne crucial aspect of any operating system is its performance.A good operating system should be efficient and provide fast response times. After testing and using the operating system extensively, we found it to perform admirably. It boots up quickly, and the overall system responsiveness is smooth. Resource allocation is handled well, with tasks running seamlessly without noticeable delays.User InterfaceA user-friendly and intuitive interface is essential for anoperating system. The operating system being reviewed demonstrates an elegant and visually appealing user interface. The layout is well-organized, making it easy to navigate through different programs and settings. The graphical design is pleasant, with icons representing various applications and files. Additionally, customization options allow users to personalize their desktop and arrange icons according to their preferences.SecurityProtecting users' data and ensuring system security are vital aspects of an operating system. The reviewed operating system excels in this area, providing robust security measures. It offers a built-in firewall to protect against unauthorized access and malicious software. The user is also prompted to create strong passwords and enables multi-factor authentication for increased security. Regular software updates ensure the latest security patches, safeguarding against potential vulnerabilities. CompatibilityCompatibility with various hardware and software is crucial foran operating system. The reviewed operating system supports a wide range of devices, including both older and newer hardware models. It integrates seamlessly with different printers, scanners, and other peripherals. Moreover, it provides extensive software compatibility, allowing users to install and run various applications without issues.Additional FeaturesApart from the core functionalities mentioned above, this operating system offers a range of additional features that enhance the user experience. Some notable features include:1. Virtual desktops: Users can create and switch between multiple virtual desktops, allowing for a more organized and efficient workflow.2. File encryption: The operating system provides a built-in encryption feature that allows users to encrypt sensitive files, ensuring data privacy and protection.3. Voice recognition: The operating system integrates voice recognition technology, enabling users to perform tasks usingvoice commands, thus making it more accessible for individuals with disabilities.4. Task manager: A comprehensive task manager displays active processes, resource usage, and allows users to manage and terminate processes if necessary.ConclusionOverall, the reviewed operating system performs exceptionally well in terms of performance, user interface, security, and compatibility. Its sleek design and intuitive user interface make it a pleasure to use. The operating system's security measures reassure users about the safety of their data. Compatibility with a wide range of devices and software ensures a seamless and hassle-free experience. The additional features further enhance productivity and accessibility. Based on these evaluations, we highly recommend this operating system as a reliable and efficient choice.。

《计算机专业英语》Unit 5 What is Operating System

The operating system is a huge management control procedures, broadly include the following five aspects of management functions: process and processor management, operations management, storage management, device management, document management.
The patterns are very diverse operating systems; OS can be installed on different machines from simple to complex, from the phone's embedded systems to large-scale supercomputer operating system. Many operating systems, the definition of manufacturer of the OS is not much consensus, for example, that some OS integrated graphical user interface, and some OS to use only a text interface, while the graphical interface as a non-essential applications.
资源, 财力, 办法, 智谋
经营, 管理, 处理, 操纵, 驾驶, 手段
Novell公司出的网络操作系统
植入的, 深入的, 内含的

operating system《操作系统》ch12-mass-storage system

12.7
Disk Attachment
Host-attached storage accessed through I/O ports talking to I/O busses SCSI itself is a bus, up to 16 devices on one cable, SCSI initiator requests operation and SCSI targets perform tasks
12.10
Disk Scheduling
The operating system is responsible for using hardware efficiently — for the disk drives, this means having a fast access time and disk bandwidth. Access time has two major components
Chapter 12: Mass-Storage Systems
整理课件
Chapter 12: Mass-Storage Systems
Overview of Mass Storage Structure Disk Structure Disk Attachment Disk Scheduling Disk Management Swap-Space Management RAID Structure Disk Attachment Stable-Storage Implementation Tertiary Storage Devices Operating System Issues Performance Issues
Seek time is the time for the disk are to move the heads to the cylinder containing the desired sector. Rotational latency is the additional time waiting for the disk to rotate the desired sector to the disk head.

LabWindows CVI实时模块入门指南说明书

Getting Started with the LabWindows/CVI Real-Time™™ModuleThis document provides an introduction to the LabWindows™/CVI™ Real-Time Module. Refer to this document for installation and configuration instructions and information about creating a real-time (RT) project.Installing the Real-Time Module Software on a Host ComputerYou must first install the Real-Time Module software on a host computer. Then you can configure and install software on the RT target.To install and use the Real-Time Module software, you must have the following:•Free Disk Space—In addition to the minimum system requirements for LabWindows/CVI, you must have at least 250 MB of free disk space for the Real-Time Module software. Refer to the LabWindows/CVI Release Notes for minimum system requirements.•RT Target—The LabWindows/CVI Real-Time Module supports NI RT Series PXI controllers, NI Real-Time Industrial Controllers, stand-alone NI CompactDAQ systems, and desktop PCs converted to RT targets.•Refer to the Using Desktop PCs as RT Targets with the Real-Time Module document for more information about converting a desktop computer to an RT target.Refer to the LabWindows/CVI Real-Time Module Readme for a step-by-step guide to installing the LabWindows/CVI Real-Time Module. You can access the LabWindows/CVI Real-Time Module Readme by selecting Start»All Programs»National Instruments»LabWindows/CVI version»LabWindows/CVI Real-Time Module Readme.Configuring the RT T argetAfter you install LabWindows/CVI and the RT module, you must use Measurement & Automation Explorer (MAX) to configure the RT target and to install software and drivers on the RT target. MAX provides access to NI devices and systems and can communicate with networked RT targets, also known as remote systems.Complete the following steps to configure the RT target. The following sections describe these steps in more detail.1.Boot the RT target into LabVIEW RT.2.Configure network settings.2| |Getting Started with the LabWindows/CVI Real-Time Module3.Install software on the RT target.4.Configure I/O.5.Configure system settings.6.Configure time settings.Refer to the Measurement & Automation Explorer Help for a complete tutorial aboutconfiguring the RT target. Select Help»MAX Help to access this help file, and then refer to the MAX Remote Systems Help section.Tip The Measurement & Automation Explorer Help refers to the LabVIEWReal-Time Module. However, you can apply the same concepts when you use theLabWindows/CVI Real-Time Module.Booting the RT Target into LabVIEW RTBefore you begin configuration, make sure your remote system is booted into LabVIEWReal-Time. If your RT target came with only LabVIEW Real-Time preinstalled on its hard drive, the system is already set up to boot into LabVIEW Real-Time. Many NI RT targets have DIP switches or BIOS settings for booting into LabVIEW Real-Time. For more information, refer to the Booting Into the LabVIEW Real-Time Module topic in the Measurement & Automation Explorer Help .You can permanently format the hard drive and configure it to boot directly into RT using the Tools»Desktop PC Utility USB Drive command in MAX.Configuring Network SettingsNoteFor the initial configuration, you must connect networked RT targets to thesame network subnet as the host computer from which you launch MAX.1.Connect the RT target to the network and power on the target.2.Launch MAX and expand the Remote Systems item in the MAX configuration tree.3.Select the RT target from the Remote Systems list. Some RT targets will be listed with an automatically configured name or IP address while other targets will be listed as 0.0.0.0.4.Specify a name for the RT target in the System Settings tab.5.Configure the IP address settings in the Network Settings tab using one of the followingoptions:•Select the DHCP or Link Local item from the Configure IPv4 Address option to obtain an IP address automatically.•Select the Static item from the Configure IPv4 Address option and specify anIP address.6.Click Save to commit the changes.7.Click Yesto reboot the RT target when prompted.Getting Started with the LabWindows/CVI Real-Time Module |© National Instruments |3Installing Software on the RT TargetUse the LabVIEW Real-Time Software Wizard in MAX to install the software and drivers from the host computer on the RT target. With the LabVIEW Real-Time Software Wizard, you can view and change the software that is installed on the target. Click Help in the wizard for more information about installing and uninstalling software on the RT target.Complete the following steps to launch the LabVIEW Real-Time Software Wizard:1.Launch MAX.2.Find and expand your RT target under the Remote Systems item in the MAX configurationtree, right-click Software , and select Add/Remove Software .When you select Add/Remove Software , MAX launches the LabVIEW Real-TimeSoftware Wizard. This displays all the National Instruments software and drivers installed on the host computer that you can install on a selected RT target.3.Select the software you want to install on the RT target, click the icon next to the software,and select Install the feature .Some components are automatically included as dependencies of other components. For more information about the features listed in the wizard, select the feature to view a description.The following list describes components you might commonly install.NoteIf you have multiple versions of a component installed on the host computer,the most recent version is selected by default. You can choose to install anotherversion.•Ethernet Drivers —MAX automatically selects the appropriate Ethernet driver(s) forthe RT target when you install the LabWindows/CVI Run-Time Engine for RTcomponent.•LabVIEW Real Time —MAX selects this item automatically when you install the LabWindows/CVI Run-Time Engine for RT component.–NI RT Extensions for SMP (MultiCore Support)—Install this item to takeadvantage of parallel processing on a multiple-CPU system.NoteSingle-CPU systems perform best without the NI RT Extensions for SMP .Also, some applications, such as those that consist mainly of single-point I/O, canachieve lower latency on a multicore system by using a single CPU without the NI RT Extensions for SMP .–Microsoft Visual Studio 2008 Runtime Support —Install this item if your application requires additional DLLs built with Visual Studio 2008.•LabWindows/CVI Network Streams for RT —Install this item if your application uses functions from the Network Streams Library. •LabWindows/CVI Network Variable for RT —Install this item if your applicationuses functions from the Network Variable Library.•LabWindows/CVI Run-Time Engine for RT—Install this item to add support for LabWindows/CVI RT applications on the RT target. This component is required forall LabWindows/CVI RT applications.•Language Support for LabVIEW RT—Install this item if you are using strings in your RT application containing ASCII characters above 127 or multibyte characters.After installing this item on the RT target, you can configure the locale in MAX byselecting the target in the Remote Systems item in the MAX configuration tree,selecting the System Settings tab, and modifying the Locale option.•NI Hardware Drivers—Install the appropriate drivers for any other hardware libraries that you use in your application. For example, install the NI-DAQmxcomponent if your application uses functions from the NI-DAQmx Library.•Network Variable Engine—MAX automatically selects this item when you install the LabWindows/CVI Network Variable for RT component.•NI Web-Based Configuration and Monitoring—Install this item to use a Web browser to monitor and configure an RT target.•State System Publisher—Install this item to monitor CPU and memory usage for an RT target from the NI Distributed System Manager.•USB Support—Install this item to enable support for accessing USB thumbdrives.•Variable Client Support for LabVIEW RT—MAX automatically selects this item when you install the LabWindows/CVI Network Variable for RT component. 4.When you finish selecting the software you want to install, click Next and continuefollowing the instructions on the screen.Configuring I/OYou must configure any National Instruments I/O devices before you can use them from a LabWindows/CVI RT application. For information about how to correctly configure I/O devices, refer to the documentation for that hardware.Configuring System Settings1.Select the System Settings tab to configure system-level settings for the RT target.2.Configure the Locale option to match the language you use for strings in your RTapplication. This option is available only when you install the Language Support for LabVIEW RT component on the RT target. This option determines the code page that LabWindows/CVI uses when processing strings containing ASCII characters above 127 or multibyte characters.Configuring Time Settings1.Select the Time Settings tab to configure date and time settings for the RT target.e the Time Zone option to configure the time zone for the RT target. You can use thissetting with time and date functions to provide accurate time information relative to the time zone setting.4||Getting Started with the LabWindows/CVI Real-Time ModuleUsing NI Web-Based Monitoring and ConfigurationIf you install NI Web-Based Monitoring and Configuration, you can use a Web browser to monitor and configure the RT target.Configuration. If you have not installed Microsoft Silverlight, NI Web-BasedMonitoring and Configuration prompts you to do so.1.In a Web browser, enter the URL http://[IP address of the RT target] toaccess Web-based monitoring and configuration for the remote system.2.Click the Login button in the top-right corner of the page.3.Enter Admin in the User name field.4.Leave the Password field blank.5.Click the OK button.6.When you log in, you can view and change system, network, security, and time settings;view console output remotely; access the file system remotely; and so on.For more information about NI Web-Based Monitoring and Configuration, refer to the LabWindows/CVI Real-Time Module Help.Configuring an RT ProjectAfter you configure the RT target, you can create an RT application on the host computer and then run the application on an RT target. The applications that you create with the LabWindows/CVI Real-Time Module are DLLs.Complete the following steps to create a DLL and specify an RT target directly from LabWindows/CVI.1.Create a project in LabWindows/CVI using RTmain instead of main as the entry pointfunction for the program. Select Edit»Insert Construct»RTmain to insert the RTmain code into the program source.2.Select Build»Configuration»Debug or Build»Configuration»Release to specify theactive configuration for the project.3.Select Build»Target Type»Dynamic Link Library to configure the project to generate aDLL.4.Select Build»Target Settings to open the Target Settings dialog box. Select Real-timeonly in the Run-time support option. If you specify this option, LabWindows/CVI does not link to the entire set of LabWindows/CVI libraries but instead links to only thoselibraries supported on an RT system.5.Click OK to exit the dialog box.6.Select Build»Build to create the DLL.You also can use a project template to create an RT DLL. The project template includes basicsettings for RT projects described in the preceding section. To select a project template,Getting Started with the LabWindows/CVI Real-Time Module|© National Instruments|5select File»New»Project from Template. In the New Project from Template dialog box, select Real-Time Target Application.Specifying an RT TargetComplete the following steps to select the RT target on which to run your RT application.1.Select Run»Select Execution Target for Debugging to view a list of previouslyconfigured RT targets. Select the RT target you want to use from the list, if it is available.2.To configure a new RT target, select Run»Select Execution Target for Debugging»NewExecution Target.3.In the New Real-Time Execution Target dialog box, enter the computer name or IP addressof the RT target in the Hostname/IP Address option and click OK to exit the dialog box. Running an RT ApplicationSelect Run»Debug Project to run your RT application.warning message. Click Continue to download and run the release DLL on the RTtarget.LabWindows/CVI automatically builds the DLL and downloads the DLL and any DLLs that are statically linked to it onto the specified RT target. LabWindows/CVI places the files that it automatically downloads in the NI-RT\CVI\temp folder. LabWindows/CVI empties the folder when you reset the RT device.While you run your RT application, LabWindows/CVI displays a <<Running on target>> menu in the upper left corner of the LabWindows/CVI environment. The menu contains the following options, which you can use for debugging and for shutting down the RT application:•Toggle Breakpoint—Turn on or turn off a breakpoint on the selected line when a Source window is active.•Break Execution—Suspend execution of the program.•Simulate RT Shutting Down—End program execution. This option causes the RTIsShuttingDown function to return 1, giving the RT application an opportunity to run any necessary cleanup code and exit. The RT target does not reboot.•Abort Execution and Reboot Target—End program execution and reboot the RT target.The application cleanup code is not guaranteed to finish running before the RT target reboots.•Disconnect from RT target—Disconnect LabWindows/CVI from the RT target while theRT application continues running on the target. Once you disconnect from the RT target,you cannot reconnect LabWindows/CVI to the RT application that is running.6||Getting Started with the LabWindows/CVI Real-Time ModuleDebugging an RT ApplicationIf you select Build»Configuration»Debug, you can debug the DLL from the LabWindows/CVI environment as you would debug any other application. For example, you can set breakpoints and watch expressions, step through code, view and edit variable values, and so on. For more information about debugging in LabWindows/CVI, refer to the Using LabWindows/CVI»Debugging Tools section of the LabWindows/CVI Help.Using the Real-Time Execution T race ToolkitThe LabWindows/CVI Real-Time Module includes a limited time full-featured evaluation of the Real-Time Execution Trace Toolkit.Use the Real-Time Execution Trace Toolkit to analyze the timing and execution of an RT application. Use the Execution Trace functions in the Real-Time Utility Library to capture the timing and execution data of functions and threads in an application running on an RT target. The Real-Time Execution Trace Tool displays the timing and event data, or trace session, on the host computer.In LabWindows/CVI, select Tools»Real-Time Execution Trace Tool to launch the Real-Time Execution Trace Tool. Refer to the LabWindows/CVI Help for more information about using the Real-Time Execution Trace Toolkit to analyze RT applications.Deploying an RT ApplicationWhen you finish developing your RT application, you can deploy it to an RT target. After you deploy the RT application, the RT application runs automatically every time the RT target reboots.Select Run»Install Program to Real-Time Execution Target to deploy your RT application. This option performs the following actions:•Checks that the release configuration of the DLL has been built; if not, LabWindows/CVI prompts you to build the DLL or cancel.•Deploys the release DLL and any statically linked DLLs to the NI-RT\CVI folder on the RT target.•Sets the release DLL as a startup DLL.•Displays a dialog box indicating that the DLL was copied and prompting you to reboot the RT target.If you have additional support files that you need to deploy, complete the following steps:1.Select Run»Manage Files on Real-Time Execution Target to launch theLabWindows/CVI Real-Time File Copy Utility.2.Click Add Files and browse to any support files that your application requires. The utilityimmediately copies the files to the NI-RT\CVI folder on the RT target.3.Click Done when you finish adding support files.Getting Started with the LabWindows/CVI Real-Time Module|© National Instruments|7Where to Go from HereRefer to the following resources for more information about the LabWindows/CVI Real-Time Module:•The LabWindows/CVI Real-Time Module Help section of the LabWindows/CVI Help includes conceptual information about real-time programming techniques, application architectures, and Real-Time Module software features you can use to create real-time applications. Select Help»Contents in LabWindows/CVI to access the LabWindows/CVI Help.•Use the NI Example Finder, available by selecting Help»Find Examples in LabWindows/CVI, to browse or search for example programs. You also can access the example programs from the samples\CVI samples\realtime directory.Refer to the NI Trademarks and Logo Guidelines at /trademarks for more information on National Instruments trademarks. Other product and company names mentioned herein are trademarks or trade names of their respective companies. For patents covering National Instruments products/technology, refer to the appropriate location: Help»Patents in your software, the patents.txt file on your media, or the National Instruments Patents Notice at /patents. You can find information about end-user license agreements (EULAs) and third-party legal notices in the readme file for your NI product. Refer to the Export Compliance Information at /legal/export-compliance for the National Instruments global trade compliance policy and how to obtain relevant HTS codes, ECCNs, and other import/export data.© 2007–2013 National Instruments. All rights reserved.374686E-01Aug13。

操作系统安装与配置实验报告

操作系统安装与配置实验报告英文回答：Operating System。

Installing an operating system (OS) is a relatively straightforward process, but it can be daunting if you've never done it before. The first step is to choose an OS. There are many different OSes available, so it's important to do your research and find one that fits your needs. Once you've chosen an OS, you'll need to download it. You can do this from the manufacturer's website or from a third-party website.Once you've downloaded the OS, you'll need to burn it to a DVD or USB drive. To do this, you'll need a burning program. There are many different burning programs available, so you can choose one that you like. Once you've burned the OS to a DVD or USB drive, you'll need to insert it into your computer and restart it. Your computer willboot from the DVD or USB drive and start the installation process.The installation process will vary depending on the OS you're installing, but it will generally involve choosing a language, accepting the license agreement, and selecting a partition to install the OS on. Once you've completed the installation process, you'll need to configure your OS. This will involve setting up your user account, installing drivers, and customizing your settings.Configuration。

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operating system操作系统-ch08-main memory-57

Main memory usually into two partitions:
Resident operating system, usually held in low memory with interrupt vector
User processes then held in high memory
8.10
Dynamic relocation using a relocation register
8.11
Dynamic Loading
Routine is not loaded until it is called Better memory-space utilization; unused routine is never
8.13
8.2 Swapping
A process can be swapped temporarily out of memory to a backing store, and then brought back into memory for continued execution
Backing store – fast disk large enough to accommodate copies of all memory images for all users; must provide direct access to these memory images
Logical (virtual) and physical addresses differ in execution-time address-binding scheme
8.9
Memory-Management Unit (MMU)

MPH_Presentation

7 Pillars of Quality
Avedis Donabedian – Father of Quality Assurance • • • • • • • Efficacy Efficiency Optimality Acceptability Legitimacy Equity Cost
Donabedian, A. (1966). Evaluating the quality of medical care. Milbank Memorial Fund Quarterly, 44,166–206.
Identification of Clinical Incidents
• • • • • • • • Incident Monitoring Systems e.g., AIMS, RiskMAN Sentinel Event Reporting Limited Adverse Occurrence Screening (LAOS) Medico-Legal Claims Occupational Health & Safety Incident Reporting Complaints i.e., Consumer Feedback, Participation Accreditation / Certification Other e.g., Clinical Indicators
• • • • • Identify what might be going wrong Prioritise problem areas that need fixing Develop a solution to the problem Implement the solution Evaluate the outcome

虚拟仪器(英汉互译)

LabVIEWLabVIEW is a highly productive graphical programming language for building data acquisition an instrumentation systems.With LabVIEW, you quickly create user interfaces that give you interactive control of your software system. To specify your system functionality,you simply assemble block diagrams - a natural design notation for scientists and engineers. Tis tight integration with measurement hardware facilitates rapid development of data acquisition ,analysis,and presentation bVIEW contains powerful built -in measurement analysis and a graphical compiler for optimum performance. LabVIEW is available for Windows 2000/NT/Me/9x, Mac OS, Linux, Sun Solaris, and HP-UX, and comes in three different development system options.Faster DevelopmentLabVIEW accelerates development over traditional programming by 4 to 10 times! With the modularity and hierarchical structure of LabVIEW, you can prototype ,design, and modify systems in a short amount of time. You can also reuse LabVIEW code easily and quickly in other applications.Better InvestmentUsing a Lab VIEW system, each user has access to a complete instrumentation laboratory at less than the cost of a single commercial instrument. In addition, user configurable LabVIEW systems are flexible enough to adapt to technology changes, resulting in a better bong-term investment.Optimal PerformanceAll LabVIEW applications execute at compiled speed for optimal performance. With the LabVIEW Professional Development System or Application Builder, you can build stand-alone executables or DLLs for secure distribution of your code. You can even create shared libraries or DLLs to call LabVIEW code from other programming languages.Open Development EnvironmentWith the open development environment of LabVIEW, you can connect to other applications through ActiveX, the Web, DLLs, shared libraries, SQL(for databases), DataSocket, TCP/IP,and numerous other e LabVIEW to quickly create networked measurement and automation systems that integrate the latest technologies in Web publishing and remote data sharing. LabVIEW also has driver libraries available for plug-in data acquisition, signal conditioning , GPIB,VXI,PXI, computer-based instruments,serial protocols, image acquisition, and motion control. In addition to the LabVIEW development systems, National Instruments offers a variety of add-on modules and tool sets that extend the functionality of LabVIEW .This enables you to quickly build customizable, robust measurement and automation systems.LabVIEW Datalogging and Supervisory Control ModuleFor high channel count and distributed applications, the LabVIEW Datelogging and Supervisory Control Module provides a complete solution. This module deliversI/O management, event logging and alarm management, distributed logging, historical and real-time trending, built-in security, configurable networking features, OPC device connectivity, and over 3,300 built-in graphics.LabVIEW Real-TimeFor applications that require real-time performance, National Instruments offers LabVIEW Real-Time. LabVIEW Real-Time downloads standard LabVIEW code to a dedicated hardware target running a real-time operating system independent from Windows.LabVIEW Vision Development ModuleThe LabVIEW Vision Development Module is for scientists, automation engineers,and technicians who are developing LabVIEW machine vision and scientific imaging applications. The LabVIEW Vision Development Module includes IMAQ Vision, a library of vision functions, and IMAQ Vision Builder, an interactive environment for vision applications. Unlike any other vision products, IMAQ Vision Builder and IMAQ Vision work together to simplify vision software development so that you can apply vision to your measurement and automation applications.Countless ApplicationsLabVIEW applications are implemented in many industries worldwide including automotive, telecommunications, aerospace, semiconductor, electronic design and production, process control, biomedical, and many others, Applications cover all phases of product development from research to design to production and to service. By leveraging LabVIEW throughout your organization you can save time and money by sharing information and software.Test and MeasurementLabVIEW has become an industry-standard development tool for test and measurement applications. With Test Stand, LabVIEW-based test programs, and the industry's largest instrument driver library, you have a single, consistent development and execution environment for your entire system.Process Control and Factory AutomationLabVIEW is used in numerous process control and factory automation applications.Many scientists and engineers look to LabVIEW for the high speed, high channel count measurement and control that graphical programming offers.For large, complex industrial automation and control applications, the LabVIEW Data logging and Supervisory Control Module provides the same graphical programming as LabVIEW, but is designed specifically for monitoring large numbers of I/O points, communicating with industrial controllers and networks, and providing PC-based control.Machine Monitoring and ControlLabVIEW is ideal for machine monitoring and predictive maintenance applications that need deterministic control, vibration analysis, vision and image processing, and motion control. With the LabVIEW platform of products including LabVIEW Real-Time for real-time deterministic control and the LabVIEW Data logging and Supervisory Control Module, scientists and engineers can create powerful machine monitoring and control applications quickly and accurately.Research and AnalysisThe integrated LabVIEW measurement analysis library provides everything you need in an analysis package. Scientists and researchers have used LabVIEW to analyse and compute real results for biomedical, aerospace, and energy research applications, and in numerous other industries. The available signal generation and processing, digital filtering, windowing, curve-fitting, For specialized analysis, such as joint time-frequency analysis, wavelet,and model-based spectral analysis, LabVIEW offers the specially designed Signal Processing Toolset.The Sound and Vibration Toolset offers octave analysis, averaged and nonaveraged frequency analysis, transient analysis, weighted filtering, and sound-level measurement, and more.Draw Your Own SolutionWith LabVIEW, you build graphical programs called virtual instruments (VIs) instead of writing text-based programs. You quickly create front panel user interfaces that give you the interactive control of your system. To add functionality to the user interface, you intuitively assemble block diagrams- a natural design notation for engineers and scientists.Create the Front PanelOn the front panel of your VI, you place the controls and data displays for your system by selecting ob jects from the Controls palette, such as numeric displays, meters, gauges, thermometers, LEDs, charts,and graphs.When you complete and run your VI,you use the front panel to control your system whether you move a slide, zoom in on a graph, or enter a value with the keyboard.Construct the Graphical Block DiagramTo program the VI, you construct the block diagram without worrying about the syntactical details of text-based programming languages. You do this by selecting objects (icons) from the Functions palette and connecting them together with wires to transfer data among block diagram objects. These objects include simple arithmetic functions, advanced acquisition and analysis routines, network and file I/O operations, and more.Dataflow ProgrammingLabVIEW uses a patented dataflow programming model that frees you from the linear architecture of text-based programming languages. Because the execution order in LabVIEW is determined by the flow of data between nodes,and not by sequential lines of text,you can create block diagrams that execute multiple operations in parallel. Consequently, LabVIEW is a multitasking system capable of running multiple execution threads and multiple VIs in parallel.Modularity and HierarchyLabVIEW VIs are modular in design, so any VI can run by itself or as part of another VI. You can even create icons for your own VIs, so you can design a hierarchy of VIs that serve as application building blocks. You can modify, interchange, and combine them with other VIs to meet your changing application needs.Graphical CompilerIn many applications, execution speed is critical. LabVIEW is the only graphical programming system with a compiler that generates optimized code with execution speeds comparable to compiled C programs. You can even use the LabVIEW profiler to analyse and optimize time-critical operations. Consequently, you increase your productivity with graphical programming without sacrificing execution speed.Measurements and MathematicsLabVIEW includes a variety of other measurement analysis tools. Examples include curve fitting, signal generation, peak detection, and probability and statistics. Measurement analysis functions can determine signal characteristics such as DC/RMS levels, total harmonic distortion (THD),impulse response, frequency response, and cross-power spectrum. LabVIEW users can also deploy numerical tools for solving differential equations, optimization, root finding, and other mathematical problems.In addition, you can extend these built-in capabilities by entering MATLAB or HIQ scripts directly in your LabVIEW programs. For charting and graphing, you can rely on the built-in LabVIEW 2D and 3D visualization tools. 2D tools include features such as autoscaling X and Y ranges, reconfigurable attributes (point/line styles, colors, and more)and cursors, Microsoft Windows users can employ OpenGL-based 3D graphs and then dynamically rotate, zoom, and pan these graphs with the mouse.Development SystemThe LabVIEW Professional Development System facilitates the development of high-end, sophisticated instrumentation systems for developers working in teams, users developing large suites of VIs, or programmers needing to adhere to stringent quality standards.Built on the Full Development System, the Professional Development System also includes the LabVIEW Application Builder for building stand-alone executables and shared libraries (DLLs）and creating distribution kits. In addition, the development system furnishes source code control tools and offers utilities for quantitatively measuring the complexity of your applications. With graphical differencing, you can quickly identify both cosmetic and functional differences between two LabVIEW applications.We include programming standards and style guides that provide direction for consistent LabVIEW programming methodology. The system also contains quality standards documents that discuss the steps LabVIEW users must follow to meet internal regulations or FDA approval. The Professional Development System operates on Windows 2000/NT/Me/9x,Mac OS, HP-UX, and Linux.LabVIEW Full Development SystemThe LabVIEW Full Development System equips you with all of the tools you need to develop instrumentation systems. It includes GPIB, VISA, VXI, RS-232, DAQ, and instrument driver libraries for data acquisition and instrument control. The measurement analysis add DC/RMS measurements, single tone analysis, harmonic distortion analysis, SINAD analysis, limit testing, signal generation capabilities, signal processing, digital filtering, windowing, curve fitting, statistics, and a myriad of linear algebra and mathematical functions. The development system also provides functions for direct access to DLLs, ActiveX, and other external code. Other features of the system include Web publishing tools, advanced report generation tools, theability to call MATLAB and HiQ scripts, 3D surface, line, and contour graphs, and custom graphics and animation. The Full Development System operates on Windows 2000/NT/Me/9x, Mac OS, HP-UX, and Linux.LabVIEW Base PackageUse the LabVIEW Base Package, the minimum LabVIEW configuration, for developing data acquisition and analysis, instrument control, and basic data presentation. The Base Package operates on Windows 2000/NT/Me/9x.Debug License for LabVIEWIf you deploy LabVIEW applications, including LabVIEW tests for use with Test Stand, the debug license allows you to install the LabVIEW development system on the target machines so you can step into your test code for complete test debugging. This license is not intended for program development.虚拟仪器汉语翻译虚拟仪器（Labview）虚拟仪器是一种高效的编程语言，主要用于构建数据采集与监测系统图形化。

办公台式电脑使用流程

办公台式电脑使用流程The process of setting up and using an office desktop computer typically involves several steps:1.Unboxing and Setup:•Unbox the desktop computer and its peripherals (monitor, keyboard, mouse, cables).•Connect the monitor, keyboard, mouse, and power cables to the appropriate ports on the computer and poweroutlet.•Power on the computer and monitor.2.Operating System Setup:•Follow the on-screen instructions to set up theoperating system (e.g., Windows, macOS, Linux).•Configure language, time zone, user accounts, and network settings as needed.•Install necessary drivers for hardware components if not automatically detected by the operating system.3.Software Installation:•Install essential software applications such as office productivity suites, web browsers, antivirus software, andany specific software required for work tasks.•Ensure that all software is properly licensed and up-to-date with the latest patches and updates.4.Data Migration:•Transfer any necessary files, documents, and settings from previous computers or backup storage to the new desktop computer.•Ensure data integrity and security during the migration process.5.Peripheral Configuration:•Configure additional peripherals such as printers, scanners, and external storage devices as needed.•Install necessary drivers and software for peripheral devices to ensure compatibility and functionality.6.Security Measures:•Set up security measures such as user account passwords, encryption, and firewalls to protect sensitive data and prevent unauthorized access.•Install and configure antivirus software to detect and remove malware threats.7.Regular Maintenance:•Perform regular maintenance tasks such as disk cleanup, software updates, and virus scans to ensure optimal performance and security.•Back up important data regularly to prevent data loss in case of hardware failure or other unforeseencircumstances.er Training:•Provide training and support to users on how to use the desktop computer effectively and safely.•Educate users on security best practices and company policies regarding computer usage and data handling.9.Troubleshooting and Support:•Troubleshoot any technical issues or errors that may arise during the setup or usage of the desktop computer.•Provide ongoing technical support and assistance to users as needed.描述（Chinese instructions）：办公桌面电脑的设置和使用过程通常包括以下几个步骤：1.拆箱和设置：•打开桌面电脑及其外围设备（显示器、键盘、鼠标、电缆）的包装。

Components in real-time systems

Components in Real-Time SystemsDamir Isovic and Christer NorströmMälardalen University, Västerås, Sweden{damir.isovic, christer.norstrom}@mdh.seAbstractComponent-based Software Engineering (CBSE) is a promising approach toimprove quality, achieve shorter time to market and to manage the increasingcomplexity of software. Still there are a number of unsolved problems thathinder wide use of it. This is especially true for real-time systems, not onlybecause of more rigorous requirements and demanding constraints, but alsobecause of lack of knowledge how to implement the component-basedtechniques on real-time development.In this paper we present a method for development of real-time systems usingthe component-based approach. The development process is analysed withrespect to both temporal and functional constraints of real-time components.Furthermore, we propose what information is needed from the componentproviders to successfully reuse binary real-time components.Finally, we discuss a possibility of managing compositions of components andsuggest how an existing real-time development environment can be extendedto support our design method.1 IntroductionEmbedded real-time systems contain a computer as a part of a larger system and interact directly with external devices. They must usually meet stringent specifications for safety, reliability, limited hardware capacity etc. Examples include highly complex systems such as medical control equipment, mobile phones, and vehicle control systems. Most of such embedded systems can also be characterized as real-time systems, i.e., systems in which the correctness of the system depends on time factors. Real-time systems are usually used to control or interact with a physical system and the timing constraints are imposed by the environment. As a consequence, the correct behavior of these systems depends not only on the logical results of the computation but also at which time the results are produced [1]. If having failed.The increased complexity of embedded real-time systems leads to increasing demands with respect to requirements engineering, high-level design, early error detection, productivity, integration, verification and maintenance. This calls for methods, models, and tools which permit a controlled and structured working procedure during the complete life cycle of the system [2]. When applying component-based software engineering (CBSE) methodology on components. Designing reusable real-time components is more complex than designing reusable non-real-time components [3]. This complexity arises from several aspects of real-must collaborate in meeting timing constraints. Examples of timing requirements can be deadline, period time, and jitter.Furthermore, in order to keep production costs down, embedded systems resources must usually be limited, but they must perform within tight deadlines. They must also often run continuously for long periods of time without maintenance.A desirable feature in all system development, including the development of real-time systems is the possibility of reusing standard components. However, using any particular operating system or database system for a real-time application is not always feasible, since many such systems are designed to maximize the average throughput of the system but do not guarantee temporal predictability. Therefore, to guarantee predictability, we must use either specific COTS developed for real-time systems or an appropriate subset of the functionality provided by the COTS. Some commonly used real-time COTS are real-time operating systems, communication protocols (solutions), and to some extent real-time databases. This type of components provides an infrastructure to the application. Other commonly used infrastructures in non-real-time systems are JavaBeans, CORBA and COM. However, they are seldom used for real-time systems, due to their excessive processing and memory requirements and unpredictable timing characteristics, which is of utmost importance in the class of application we consider. They have, however, one desirable property which is flexibility, but predictability and flexibility have often been considered as contradicting requirements, in particular from the scheduling perspective. Increased flexibility leads to lower predictability. Hence, a model for hard real-time systems cannot support flexibility to the same extent as the above mentioned infrastructures.Further, we require to reuse application specific components. Example of two application specific component models are IEC-1131 [5] which is a standard for programming industrial[4]. Both these models provide support for hierarchical decomposition, parameterization,similar to pipes and filters model, the difference is that the pipe only accommodates one data item, which means if the data has not already been processed when the new data arrives, it will be overwritten. However, both models lack the ability to specify timing attributes besides period time and priority which is not sufficient to specify timing sensitive systems.The development of standard real-time components which can be run on different HW platforms is complicated by the components having different timing characteristics on different platforms. Thus a component must be adapted and re-verified for each HW-platform to which it is ported, especially in safety-critical systems. Hence, we need to perform a timing analysis for each platform to which the system is ported. Given a system composed of a set of well-tested real-time components, we still face the composability problem. Besides guaranteeing the functional behavior of a specific component, the composition must also guarantee that the communication, synchronization and timing properties of the components and the system are retained. The composability problem with respect to timing properties, which we refer to as timing analysis, can thus be divided into (1) verifying that the timing properties of each component in the composed system still hold and (2) schedulability analysis (i.e. system-wide temporal attributes such as end-to-end deadlines can be fulfilled). Timing analysis is performed at two levels, the task level and the system level. At the task level the worst case execution time (WCET) for each task is either analyzed or estimated. If the execution time is measured, we can never be sure that we have determined the worst case. On the other hand if we use analysis, we must derive a safe value for the execution time. The estimated execution time must be greater than or equal to the real worst case and in the theory provided, the estimate can be excessive. The challenge here is thus to derive a value as close as possible to the real worst case execution time. Puschner gives a good introduction to this problem in the seminal paper [7]. At system level we analyze to determine if the systemexample, analysis for priority-based systems and pre-run-time scheduling techniques [8][9]. Both kinds of analysis have been proven to be useful in industrial applications [10][11]. When designing a system, we can assign time budgets to the tasks which are not implemented by intelligent guesses based on experience. By doing this we gain two positive effects. Firstly, the system level timing analysis can be performed before implementation, thus providing a tool for estimating the performance of the system. Secondly, the time budgets can be used as an implementation requirement. By applying this approach we make the design process less ad hoc with respect to real-time performance. In traditional system design, timing problems are first recognized when the complete system or subsystem has been implemented. If a timing problem is then detected, ad hoc optimization will be begun, this most surely making the system more difficult to maintain.The paper is organized as following: In Section 2 we present a method for system development using real-time components which support early analysis of the timing behavior as well as the synchronization and communication between components. The method enables high-level analysis on the architectural design level. This analysis is important to avoid costly re-design late in the development due to the detection in the integration test phase that the system as developed does not fulfill the timing requirements. The presented method is an extension of [10], and it is a standard top-down development process to which timing and other real-time specific constraints have been added and precisely defined at design time. The idea is to implement the same principles, but also taking into consideration features of existing components which might be used in the system. This means that the system is designed not only in accordance with the system requirements, but also with respect to existing components. This concept assumes that a library of well-defined real-time components is available. The development process requires a system specification, obtained by analyzing the customer's requirements.Furthermore, in Section 3, we propose a method for composing components and how the resulting compositions could be handled when designing real-time systems. In Section 4 we describe how an existing real-time development environment can be extended to support our design method. Finally, in Section 5, we provide guidelines about what one should be aware of when reusing and online updating real-time components.2 Designing component based real-time systemsIn this section we present a method for system development using real-time components. This method is an extension of [10], which is also in use in developing real-time systems within a to which timing and other real-time specific constraints have been added and precisely defined (or more correctly, have been predicted) at design time. The idea is to implement the same principles, but also taking into consideration features of existing components which might be used in the system. This means that the system is designed not only in accordance with the system requirements, but also with respect to existing components. This concept assumes that a library of well-defined real-time components is available. The development process requires a system specification, obtained by analyzing the customer's requirements. We assume that the specification is consistent and correct, in order to simplify the presentation of the method.The development process with real-time components is divided into several stages, as depicted in Figure 2-1. Development starts with the system specification, which is the input to components, the designer browses through the component-library and designs the system, making selections from the possible component candidates.Add newcomponentsto the libraryFigure 2-1: Design model for real-time componentsThe detailed design will show which components are suitable for integration. To select components, both real- and non real-time aspects must be considered. The scheduling and interface check will show if the selected components are appropriate for the system, if adaptation of components is required, or if new components must be developed. The process of component selection and scheduling may need to be repeated several times to refine the design and determine the most appropriate components. When a new component must be developed, it should be, (when developed and tested) entered into the component library. When the system finally meets the specified requirements, the timing behavior of the different components must be tested on the target platform to verify that they meet the timing constraints defined in the design phase. A detailed description of these steps is given below.2.1 Top-level designThe first stage of the development process involves de-composition of the system into manageable components. We need to determine the interfaces between them and to specify the functionality and safety issues associated with each component. Parallel with the decomposition, we browse the component library to identify a set of candidate components,(i.e., components which might be useful in our design).2.2 Detailed designAt this stage a detailed component design is performed, by selecting components to be used in each component from the candidate set. In a perfect world, we could design our system by only using the library components. In a more realistic scenario we must identify missingcomponents that we need according to our design but which are not available in the component library. Once we have identified all the components to be used, we can start by assigning attributes to them, such as time-budgets, periods, release times, precedence constraints, deadlines and mutual exclusion etc.A standard way of performing the detailed design is to use the WCET specified for every task which specifies the upper limit of the time needed to execute a task. Instead of relying on WCET values for components at this stage, a time budget is assigned to each component. A component is required to complete its execution within its time budget. This approach has also been adopted in [14], and shown to be useful in practice. Experienced engineers are often 2.3 SchedulingAt this point we need to check if the system's temporal requirements can be fulfilled, assuming time budgets assigned in the detailed design stage. In other words, we need to make a schedulability analysis of the system based on temporal requirements of each component. A scheduler which can handle the relevant timing attributes has been presented in [14], used.The scheduler in [14] takes a set of components with assigned timing attributes, and creates a static schedule. If scheduling fails, changes are necessary. It may be sufficient to revise the detailed design by reengineering the temporal requirements or by simply replacing components with others from the candidate set. An alternative is to return to top-level design and either select others from the library or specify new components.During the scheduling we must check that the system is properly integrated; component interfaces are to be checked to ensure that input ports are connected and that their types match. Further, if the specified system passes the test, besides the schedules, the infrastructure for communication between components will be generated.2.4 WCET verificationEven if the component supplier provides a specification of the WCET, it must be verified on the target platform. This is absolutely necessary when the system environment is not as in the component specification. We can verify the WCET by running test cases developed by the component designer and measuring the execution time. The longest time is accepted as the component WCET. Obtaining the WCET for a component is a quite complicated process, especially if the source code is not available for the performance of the analysis. For this reason, correct information about the WCET from the component supplier is essential.2.5 Implementation of new componentsNew components; those not already in the library must be implemented. A standard development process for the development of software components is used. It may happen that some of the new components fail to meet their assigned time budgets. The designer can either add these to the library for possible reuse in other projects or redesign them. In order to proceed, the target platform must be available at this stage. Once a component is implemented and verified we must determine its WCET on our target platform and verify the WCET of library components, if this has not been done before.2.6 System build and testFinally, we build the system using old and new components. We must now verify the functional and temporal properties of the system obtained. If the verification test fails, we must return to the appropriate stage of the development process and correct the error.2.7 Component libraryThe component library is the most central part of any CBSE system, since it contains binaries of components and their descriptions. When selecting components we examine the attributes available in the library. A component library containing real-time components should provide the following in addition to component identification, functional description, interface, component binary and test cases:• Memory requirements - Important information when designing memory restricted systems, and when performing trade-off analysis.• WCET test cases - Test cases which indicate the WCET of the components WCET for a particular processor family. Information about the WCET for previously used targets should be stored to give a sense of the components processor requirements.• Dependencies – Describing dependencies on other components.• Environment assumptions - Assumptions about the environment in which the component operates, for example the processor family.2.8 WCET test casesSince the timing behavior of components depends on both the processor and the memory organization, it is necessary to re-test the WCET for each target different from that specified. The process of finding the WCET can be a difficult and tedious process, especially if complete information or the source code is not available. Giving the WCET as a number does not provide sufficient information. What is more interesting in the test cases is the execution time behavior shown as a function of input parameters as shown in Figure 2-2. The execution time shows different values for the different input sub-domains.Execution timeInputFigure 2-2: An execution time graphProducing such a graph can also be a difficult and time-consuming process. In many cases, however, the component developer can derive WCET test cases by combining source code analysis with the test execution. For example, the developer can find that the execution time is independent of input parameters within an input range (this is possible for many “simple" processors used in embedded systems but not for others).The exact values of the execution time are not as important as the maximum value within input intervals, as depicted in Figure 2-3. When a component is instantiated, the WCET test how the component is instantiated.Execution timeInputFigure 2-3: Maximum execution time per sub-domain3 Composition of componentsAs mentioned earlier a component consists of one or more tasks. Several components can be composed into a more complex one. This is achieved by defining an interface for the new component and connecting the input and output ports of its building blocks, as shown in Figure 3-1.This new kind of component is also stored in the component library, in much the same way as the other components. However, two aspects are different: the timing information and the component binary. The WCET of a composed component cannot be computed since its parts may be executing with different periods. Instead we propose that end-to-end deadlines should be specified for the input to and output from the component. End-to-end deadlines are set such that the system requirements are fulfilled in the same way as the time budgets are set. These deadlines should be the input to a tool which can derive constraints on periods and deadlines for the sub-components. This possibility remains the subject of research and cannot be considered feasible today.Figure 3-1: Composition of componentsFurthermore, we specify virtual timing attributes (period, release time and deadline) of the composed component, which are used to compute the timing attributes of sub-components. For example, if the virtual period is set to P, then the period of a sub-component A should be f A * P and the period of B is f B * P, where f A and f B are constants for the composed component, which are stored in the component library. This enables the specification of timing attributes at the proper abstraction level. The binary of the composed component is not stored in the component library. Instead references to the sub-components are stored, to permit the retrieval of the correct set of binaries.4 Example: RT components in Rubus OSCurrently there are not so many real-time operating systems that have some concept of components. The Rubus operating system [19] is one of those. In this section we will describetogether with our development process. The scheduling theory behind this framework is explained in [14].4.1 RubusRubus is hybrid operating system, in the sense that it supports both pre-emptive static scheduling and fixed priority scheduling, also referred to as the red and blue parts of Rubus. The red part deals only with hard real-time and the blue part only with soft. Here we focus on the red part only.Each task in the red part is periodic and has a set of input and output ports, which are used for unbuffered communication with other tasks. This set also defines a task’s interface. A task provides the thread of execution for a component and the interface to other components in the system via the ports. In Figure 4-1 we can see an example of how a task/component interface could look like.Task state informationFigure 4-1: A task and its interface in the red model of RubusEach tasks has an entry function that which as arguments have input and output ports. The value of the input ports are guaranteed not to change during the execution of the current instance of the task, in order to avoid inconsistency problems. The entry function is re-invoked by the kernel periodically.The timing requirements of the component/task are shown in Figure 4-1. The timingrequirements, it is also possible to specify ordering of tasks using precedence relations, and mutual exclusion. For example the depicted task in is required to execute before the outputBrakeValues task, i.e., task BrakeLeftRight precedes task outputBrakeValues. A systemis composed of a set of components/tasks for which the input and output ports have been connected, as depicted in Figure 4-2.Figure 4-2: A composed system in the red model of RubusWhen the design of a system is finished, a pre run-time scheduler is run to check if the temporal requirements can be fulfilled. If the scheduler succeeds then it also generates a schedule for the design, which is later used by the red kernel to execute the system.4.2 Extensions for CBSELet’s see what is missing in Rubus and its supporting tools to make them more suitable for component based development. Firstly, there is currently no support for creating composite components, i.e., components that are built of other components. Secondly, some tool is needed to manage the available components and their associated source files, so that components can be fetched from a library and instantiated into new designs. Besides this there is a lack of real-time tools like: WCET analysis, allocation of tasks to nodes.Support for composition of components can easily be incorporated into Rubus, since only a front-end tool is needed that can translate component specifications to task descriptions. The front-end tool needs to perform the following for composition:1. assign a name to the new component2. specify input and output ports of the composition3. input and output ports are connected to the tasks/ components within the component,see Figure 4-3.4.Component: BrakeSystemFigure 4-3: Composition of components in Rubus5 Reuse of RT ComponentsDesign for reuse means that a component from a current project should require a minimum of modification for use in a future project. Abstraction is extremely valuable for reuse. When designing components for reuse, designers should attempt to anticipate as many future applications as possible. Reuse is more successful if designers concentrate on abstract rather than existing uses. The objective should be to minimize the difference between the component's selected and ideal degrees of abstraction. The smaller the variance from the ideal level of abstraction, the more frequently a component will be reused.There are other important factors which designers of reusable components must consider, they must not only anticipate future design contexts and future reuses. They must consider:• What users need and do not need to know about a reusable design, or how to emphasize relevant information and conceal that which is irrelevant.• What is expected from potential users, and what are their expectations about the reusable design.• That it is desirable, though difficult, to implement binary components, to allow users to instantiate only relevant parts of components. For example, if a user wants to use only some of the available ports of a component, then only the relevant parts should be instantiated.No designer can actually anticipate all future design contexts, when and in which environment the component will be reused. This means that a reusable component should depend as little as possible on its environment and be able to perform sufficient self-checking. In other words, it should be as independent as possible. Frequency of reuse and utility increase with independence. Thus independence should be another main area of concern when designing reusable components.An interesting observation about efficient reuse of real-time components, made by engineers at Siemens [15] is that, as a rule of thumb, the overhead cost of developing a reusablefifth reuse. Similar experience at ABB [16] shows that reusable components are exposed to changes more often than non-reusable parts of software at the beginning of their lives, until they reach a stable state.Designing reusable components for embedded real-time systems is even more complicated due to memory and execution time restrictions. Furthermore, real-time components must be much more carefully tested because of their safety-critical nature.These examples show that it is not easy to achieve efficient reuse, and that the development of reusable components requires a systematic approach in design planning, extensive development and support of a more complex maintenance process.5.1 Online Upgrades of ComponentsA method for online upgrades of software in safety-critical real-time systems has been presented in [17]. It can also be applied to component-based systems when replacing components.Replacing a component in a safety critical system can result in catastrophic consequences if the new component is faulty. Complete testing of new components is often not economically feasible or even possible, e.g., shutting down a process plant with high demands on availability can result in big financial losses. It is often not sufficient to simulate the behavior of the system including the new component. The real target must be used for this purpose.However, testing in the real system means that it must be shut down, and there is also a potential risk that the new component could endanger human life or vital systems.To overcome these problems it is proposed in [17] that the new component should be monitored to check that its output is within valid ranges. If it is not, then the original component will resume control of the system. It is assumed that the old component is reliable, but not as effective as the new component in some respect e.g., the new provides much improved control performance. This technology has been shown to be useful for control applications.A similar approach can be found in [18] where a component wrapper invokes a specific wrapper execution time must be taken into consideration, and such a system must support version management of components.In this development model we assume that a static schedule is used at run-time to dispatch the tasks, and since the schedule is static the flexibility is restricted. However, in some cases it is possible to perform online upgrades.Online upgrade of the system requires that the WCET of the new component is less or equal to the time-budget of the component it replaces. It is also required that it has the same interface and temporal properties, e.g., period and deadline. If this is not feasible, a new schedule must be generated and we must close down the system to upgrade it. Using the fault-tolerance method above, we can still do this safely with a short downtime.6 SummaryIn this paper we presented certain issues related to the use of component technology in the development of real-time systems. We pointed out the challenges introduced by using real-time components, such as guaranteeing the temporal behavior not only of the real-time components but also the entire composed system.When designing real-time systems with components, the design process must be changed to include timing analysis and especially to permit high-level analysis on an architectural design level. We presented a method for the development of reliable real-time systems using the component-based approach. The method emphasizes the temporal constraints which are estimated in the early design phase of the systems and are matched with the characteristics of existing real-time components. We outlined the information needed when reusing binary components, saved in a real-time component library.Furthermore, we proposed a method for composing components and how the resulting compositions could be handled when designing real-time systems. We also provided guidelines about what one should be aware of when reusing and online updating real-time components.References[1] Stankovic, J. and Ramamritham, K. Tutorial on Hard Real-Time Systems. IEEEComputer Society Press, 1998[2] D. Kalinsky and J. Ready. Distinctions between requirements specification and designof real-time systems. Conference proceedings on TRI-Ada '88 , 1988, Pages 426 – 432.[3] Douglas, B.P. Real-Time UML - Developing efficient objects for embedded systems.Addison Wesley Longman, Inc, 1998。

VZ-3neo 演示系统 CN说明书

N EWolfVision is a provider of systems and services to leading universities, businesses, schools, and other organizations. An acknowledged ‘technology leader’ in the Visualizer and presentation solutions market, WolfVision is the company that takes the lead, setting standards worldwide for innovative, reliable, user-friendly, high performance presentation, and collaboration solutions. Our VZ-3neo Visualizer system includes all the core features that every user requires, and it is customizable with a range of options providing maximum flexibility in system selection.With more than 40 years experience, our extensive knowledge and expertise across all application sectors enables us to offer comprehensive consultative guidance on customized combinations of hardware systems, software, apps, and accessories, which enhance communication, collaboration, and knowledge sharing across all environments. As part of each individual vSolution WolfVision offers not only pre-sales advice, but also post-sales support, training, and service, ensuring that you receive maximum benefit from your investment.Driving Knowledge CreationVZ-3neo Visualizer SystemOur VisionWhen you’ve got something to say, we believe it is important that getting your message across and making an impact should be as easy as possible.Our aim is to help you to explain it better, to give you the freedom to share your knowledge and collaborate with others - however you want, and whenever you want, when your audience is in the same room or on the other side of the world.Because knowledge matters -to all of us.90° rotation++ Video ++Key FeaturesPowerful zoom rangeSimply use the zoom wheel, and leave other settings like focusing, brightness, and white balance to be adjusted automatically.Control via room management sys-tem or computer, or use the vSolu-tion App for wireless control via a mobile device.The LAN port includes Power over Ethernet Plus (PoE+) functionality - a popular way of saving on cables and installation costs.Maximum ease of useFlexible external controlPower over Ethernet PlusNative 1080p full HD camera for presentation of content materials in unrivalled image quality.No. 1 for imaging performanceHigh quality components for out-standing mechanical quality, dura-bility, and reliability. The VZ-3neo is built to last!Visualizers built to last!Self-adhesive dry-erase working surfaces available for convenient pickup and display of handwritten content materials.vSolution Link Pro software for easy remote setup, monitoring, management, and updating of sys-tems.High speed continuous autofocus ensures crisp presentation of all on-screen content materials.Write on your Visualizer!Remote management softwareFocus on the contentAdjustment-free lighting12x zoom for outstanding flexibi-lity when displaying content on-screen. I mages are always crystal clear, even when zooming in closely on materials.No distracting hot spots or reflec-tions - and no need to adjust the light. This LED Lighting system is optimised for perfect illumination.Your WolfVision Partner:M o r e i n f o r m a t i o n :D e s i g n a n d s p e c i fi c a t i o n s s u b j e c t t o c h a n g e ! | P r i n t e d i n G e r m a n y , J a n u a r y 2020Head Office:WolfVision GmbH 6833 Klaus / Austria Tel. +43 5523 52250*************************Germany Sales Office WolfVision GmbH Tel. 0800 9828 787*************************************USA Sales Office WolfVision, Inc.Tel. +1 770 931 6802*******************Nordic Sales OfficeWolfVision Nordic (Norway)Tel. +47 9186 9736********************************Asia Sales OfficeWolfVision Pte. Ltd. (Singapore)Tel. +65 6636 1268******************************Middle East Sales OfficeWolfVision Middle East (Dubai)Tel. +971 5617 40008*********************************Japan Sales Office WolfVision Co. Ltd.Tel. +81 3 6233 9465*******************************UK Sales Office WolfVision UK Ltd.Tel. +44 1628 509 067****************************Technical specificationsCamera1-CMOS 1/3“, 30 frames per second in all resolutions Effective pixels of camera sensor 1920x1080 (2,073,600)Native signal output1080p HD (1920x1080)Converted output signals (4:3 and 5:4)UXGA (1600x1200), SXGA (1280x1024) XGA (1024x768), SVGA, (800x600)Converted widescreen output signals (16:9 and 16:10)720p HD (1280x720), WUXGA (1920x1200), WXGA (1280x800)Resolution (measured)980 linesBrightness control & White balance adjustment Automatic and manualFocusing ModesHigh speed Continuous Autofocus, Manual Focus On-screen menu and on-screen helpYesvSolution Link Pro software for remote management & firmware updatesYes, included (for Windows 10 Desktop, Windows Server 2012 R2 & 2016)Free firmware updates Yes, via USB, LAN, and vSolution Link ProZoom / Lens type12x zoom (6x optical, 2x digital), multiple-speed zoom wheel Max. object height on working surface 200mm (8.0“) in tele position 320mm (12.6“) in wide position Max. pick-up area on working surfaceLength: 290mm (11.42“), Width: 400mm (15.75“)Min. pick-up area on working surface (full resolution, optical zoom)66 x 50mm (2.6” x 2.0”)Min. pick-up area on working surface (with digital zoom)33 x 26mm (1.3” x 1.0”)Depth of focus on small object: 66 x 36mm (2.6” x 1.4”)15mm (0.6“)Depth of focus on large object: 360 x 200mm (14.1” x 7.9”)260mm (10.2“)Light sourceMaintenance-free, high-brightness LED light system (high light output, low power consumption), lamp lifetime: 30,000 hours UVC (Windows, Linux & macOS), PTP (Picture T ransfer Protocol)YesReflection-free area on working surface Yes, entire working surface Intelligent folding systemY es, mechanical arm User-defined settings on USB stick Y es User programmable presets 1Swivel plate with 90° rotationOptional External computer input/input switch Yes, HDMI Live to freeze comparison (Picture in Picture)YesBuilt-in digital scaler for the computer input Yes (processes the signal from HDMI input for HDMI output)Image memory1 image freezeAlternative image display Negative image / negative-blue image / black and white imageConnectors1x HDMI In, 1x HDMI Out, 1x LAN port, 1x mini USB 2.0 device port, 1x USB 2.0 host port Advanced controlling with professional protocol Yes, via LAN and USBvSolution App compatibleYes, wireless control via a mobile device (app available for iOS, iPadOS, Android, and Windows)Dimensions in operation (L x W x H)488mm x 305mm x 525mm (19.2“ x 12“ x 20.7“)Dimensions when folded (L x W x H)574mm x 305mm x 135mm (22.6“ x 12“ x 5.3“)Weight3.76kg (8.3lbs)Anti-theft devices T -Lock (Kensington® Lock), and table lock boltPowerExternal desktop power pack 12V: multi range 100-240V , 24W, Power over Ethernet Plus (IEEE 802.3at-2009 standard)Included accessories Cable shield, power supply with cord 1.8m (5’11”), LAN cable 1.8m (5‘11“), mini USB cable 1.8m (5‘11“)Optional accessories Dry-erase working surface, carrying case Warranty / Made in5 years / EU Austria。

Real-time software implementation of NTSC Analog TV on Sandblaster R ○ SDR platform

Real-time software implementation of NTSC Analog TV on Sandblaster R SDR platform Vladimir Kotlyar,Daniel Iancu,John Glossner,Hua Ye,Andrei IancuSandbridge Technologies,Inc.{vkotlyar,diancu,jglossner,huaye,aiancu}@Abstract—This paper describes the real-time soft-ware implementation of NTSC Analog TV on the Sand-blaster SDR platform.The platform supports real-time execution of a number of communication proto-cols and multimedia applications,including:802.11b, WCDMA,GSM,GPS,MPEG4,H.264and others. Our implementation of analog TV runs in real-time on Sandblaster evaluation board and produces high-quality visual output.In this paper we describe the Sandblaster SDR platform and discuss how its archi-tectural features have guided our design decisions.Index Terms—Video signal processing,parallel pro-cessing,real time systemsI.I NTRODUCTIONIt is desirable to provide analog TV viewing on a mobile platform that supports other wireless commu-nication protocols.Since each communication proto-col requires a separate chip set,PC board space and overall cost are the limiting factors.Sandbridge Tech-nologies has developed a multi-core multi-threaded Digital Signal Processing(DSP)platform called the Sandblaster DSP that is capable of executing most of the existing communication and media pro-tocols completely in software,including802.11b, WCDMA,GSM,GPS,MPEG4,and H.264[1],[2], [3].The Sandblaster processor maintains low power consumption while providing high computational throughput by dividing work among four DSP cores each running eight simultaneous hardware threads. In this paper we describe a parallel real-time imple-mentation of NTSC Analog TV on the Sandblaster platform.We focus on the task of extracting video information from the baseband signal once the ini-tial vertical and horizontal synchronization has been achieved.This video decoding task is the most com-putationally intensive and has to be performed in real-time.A companion paper[4]describes the details of the signal processing algorithms including synchro-nization.Fig.1.Sandblaster R processorWeﬁrst describe the Sandblaster hardware and software.Then we describe video encoding used in NTSC analog TV.Finally,we present and analyze the sequential algorithm and describe its parallel real-time implementation.II.S ANDBLASTER R PLATFORMA.Four coresThe Sandblaster processor(Figure1)consists of four DSP cores connected by a unidirectional ring. The cores run at600MHz.The chip is fabri-cated in90nm technology and is fully functional. Each core has a branch unit,a scalar Arithmetic Logic Unit(ALU),a Single Instruction Multiple Data (SIMD)vector unit and load/store unit.These exe-cution resources are time multiplexed equally among 8threads.Each thread has its own set of scalar and SIMD vector registers.B.Instruction set architectureA thread executes64-bit compound instructions.A compound instruction can contain up to3concur-rently executed compound operations.For example a load can be issued in parallel with an arithmetic op-eration and a branch.The following instruction com-putes the inner product of a vector with itself: Label:vmulred%ac3,%vr7,%vr7,%ac3|| lvu%vr7,%r8,8||loop0,%lc0,LabelThe vmulred operation multiplies each of four 16-bit elements contained in the vector register%vr7 with itself and accumulates the products into an ac-cumulator register%ac3.At the same time,the lvu operation increments the scalar register%r8by8and loads the next4values from the resulting address. The loop operation decrements the loop count regis-ter%lc0and repeats the instruction if the register is non-zero.Each Sandblaster core is capable of completing an instruction from a thread on every600MHz cycle pro-vided there are no stalls due to memory access.In particular,each core is capable of completing a4-way multiply-accumulate(MAC)instruction at every 600MHz cycle.Across four cores this adds up to 4*600*4=9600million MACs per second.Since core execution resources(ALU,branch,etc.) are shared equally among the8threads we can view a core as an8-way multi-processor with each processor running at600MHz/8=75MHz.We denote this per-formance as a“thread cycle”.In the rest of the paper we report memory latencies and algorithm complexity using75MHz thread cycles.C.Memory structureEach core has a32kB instruction cache.Data memory is not cached and is divided between a64kB Level1(L1)and256kB Level2(L2)memory.A load from L2memory incurs a pipeline stall.Stores into L2are issued through a FIFO and do not block unless the FIFO is full.In practice up to four threads can simultaneously store into L2without blocking. L1memory is divided into8banks of8kB each.A particular implementation detail is that there is no penalty if the parity(odd/even)of the thread is the same as the parity of the bank.There is a single cycle penalty both for loads and for stores if the parities of the thread and the bank do not match.The instruction in the inner product example will complete within a single thread cycle,if it is executed on an even thread and%r8points into an even bank. The compiler tries to ensure memory afﬁnities and the processor tools can automatically generate linker scripts that optimize memory access.D.Global address spaceAll memory regions are mapped onto a global ad-dress space.The highest order4bits of an address de-note the node on the ring.Nodes1-4refer to the DSP cores.Node0refers to the I/O node and is shown in Figure1.The I/O node is connected via an Arm High-Performance Bus(AHB)to an ARM926EJ-S processor,external memory,and peripheral devices (e.g.,USB,LCD,etc.).The devices are all memory-mapped.As an example,the address range0x40000000 through0x4FFFFFFF is mapped to core4.Theﬁrst 64kB is L1memory,the next256kB is L2.Any core can directly access any memory,except another cores L1memories.E.Costs of load/storeIn the worst case,a load from L2memory may re-quire two trips through the ring.First the request trav-els to the target core.Then the loaded data is send to the requester.The latency of this operation is at least 8thread cycles.A store to remote L2memory incurs much less penalty.The request is inserted into a FIFO at the core/ring interface.It can be processed concurrently with thread execution.F.Memory DMAEach core has two Memory Direct Memory Access (MDMA)engines.They copy data between comple-mentary regions.For example,one channel can copy from L2to L1while the other can copy from L1to L2.DMA is the most efﬁcient way of copying data between L1and L2,since each engine is capable of maximizing L2bandwidth.Four threads would have to simultaneously load from L1and store to L2in or-der to achieve the same effect.G.High-speed serial interfaceA high-speed serial interface is provided for copy-ing signal samples to/from the DSP.Incoming sam-ples(e.g.from an Analog to Digital(A/D)converter)are copied into L2memory on Core1.Outgoing sam-ples(e.g.to the Digital to Analog(D/A)converter) are copied from L2memory on Core2.Each core provides memory mapped registers to specify the region in L2to be used as a circular in-put/output buffer.III.I MPLICATIONSThe following guidelines are useful for developing parallel software for the Sandblaster platform:1)Data should be kept in L1memory as much aspossible to avoid memory miss penalties.2)Cooperating tasks should be put on threads withthe same parity(odd/even)so their data can beallocated to L1banks with the same parity. 3)Large amounts of data should be pushed toother cores either via stores or,preferably,viaMDMA.4)MDMA should be used as much as possible totransfer bulk data between memory regions. 5)SIMD vector operations should be used asmuch as possible,since they provide4-wayspeedup for typical signal processing array op-erations.IV.P ROGRAMMING ENVIRONMENTA.Supercomputer-class vectorizing compilerThe Sandblaster compiler removes the need for as-sembly language programming.The compiler auto-matically vectorizes most of the loops that occur in signal processing and media applications.It performs semantic analysis of input programs and automati-cally recognizes saturating arithmetic in ANSI C[5]. It also performs traditional optimizations such as soft-ware pipelining,loop unrolling,and memory disam-biguation.As an example,the single-instruction loop for an inner product(from Section II.B)is generated auto-matically from the following straight-forward C code: int i,s;for(i=0,s=0;i<N;i++){s+=A[k]*A[k];}Our analog TV receiver is written purely in ANSI C, without assembly language.B.Fast simulatorThe Sandblaster simulator is capable of executing over100million instructions per second on a3GHz x86computer.This is achieved by on-the-ﬂy dynam-ically translating Sandblaster instructions directly to x86instructions during simulation.The speed of sim-ulation allows for efﬁcient white box software devel-opment and often provides real-time performance of algorithms.C.RTOSThe Sandblaster real-time operating system (RTOS)implements the POSIX pthreads standard.It provides a well known API for thread management and synchronization.The RTOS also contains a library with APIs for memory DMAs and peripheral interfaces.The RTOS is capable of multiplexing an arbitrary number of software threads onto hardware threads. Software threads can be designated as pinned or non-pinned.Pinned threads are removed from the general thread scheduler and,by convention,their stacks are allocated to L1memory.Non-pinned threads can be re-scheduled any time the operating system chooses and can be allocated based on the scheduling policy implemented in pthreads.Allocation of L1memory to stacks of pinned threads provides a simple convention to help design efﬁcient code:frequently accessed data should be kept on the stack.V.A NALOG TV BASEBAND SIGNALA.Frame and line structureNTSC systems display30frames per second with 525lines within each frame[6],[7].The lines are interlaced.Theﬁrst262lines are placed at odd posi-tions(starting with1),the next263lines are placed at even positions(see Figure2).Theﬁrst20lines are called the blanking interval with lines4,5and6providing the pattern used in ver-tical synchronization.The lines following the blank-ing interval consist of the sync tip,followed by color burst and actual video data(see Figure2).The sync tip is used in horizontal synchronization.A compan-ion paper[4]describes in detail how horizontal and vertical synchronization is achieved.This paper fo-cuses on the task of decoding video signal.B.NTSC basebandVideo is encoded for transmission as follows:1)The primary color components R,G,and B aretransformed into luminance/chrominance com-ponents Y,I,and Q.The transform is linear:[Y I Q]T=M×[R G B]Fig.2.NTSC frame and linewhere M is the3×3colorspace conversion ma-trix.2)The luminance component Y is transmitted di-rectly(in baseband).3)The two chrominance components I and Qcarry color information.They are QAM modu-lated at the color sub-carrier frequency of3.58MHz.The video portion of baseband signal carries Y+ QAM(I,Q).The bandwidth of this signal is 4.2MHz.For broadcast,sound is added.It is fre-quency modulated around4.5MHz.The overall base-band encoding is:1.[Y I Q]ˆT=M×[R G B]ˆT2.V ideo=Y+QAM(I,Q)3.Baseband=V ideo+F M(Sound)(commodity)LCDRefresh fromext. memorydevelopmentboardRFA/D SB301010−bit samples14.32M/secFront−end(custom)Fig.3.Analog TV receiverVI.R ECEIVEROur receiver hardware is shown in Figure 3.A custom-made RF front-end is capable of tuning to a particular TV channel.The output is a baseband sig-nal that is sampled at14.32MHz(four times the color sub-carrier frequency).Samples are10-bits wide.A commodity A/D converted is used.Samples are fed into Sandblaster3010develop-ment board.At each rising edge of the A/D clock a sample is stored within L2memory of Core1.Each sample occupies2bytes of memory.10-bit samples are embedded into the highest bits of each stored16-bit value.VII.S EQUENTIAL ALGORITHMThe overall sequential algorithm for decoding video signals from the baseband is:1.[gain,level]=normalize(input)2.input=input∗gain+level3.video=LPF1(input)4.Y=LPF2(video)5.Sin=gen sin(color burst(input))6.I=LPF3((video−Y).∗Sin)7.Q=LPF3((video−Y).∗Sin(2:))8.[R G B]ˆT=clip(M−1∗[Y I Q]ˆT)9.pixels=B<<10|G<<5|RThe normalize()function(step1)computes the average of sync tip samples and computes the gain and level that normalize the top of the sync tip to be at 0and the bottom of sync tip to be at-200.This value is consistent with the subsequentﬁxed-point compu-tations.Step2performs the normalization.The low-passﬁlter in step3separates the video signal from sound.The result is Y+QAM(I,Q).Step4separates the Y(luminance)compo-nent using another low-passﬁlter.Observe that QAM(I,Q)=video−Y,at this point.The LPF1 and LPF2ﬁlters are implemented as32-tap FIRﬁl-ters.Color-burst is a fragment of the2.5µsec sine wave to be used in demodulating the chrominance compo-nents I and Q.For a sampling rate of2.5µsec,about 35samples are received.We generate a sine wave for the length of the video signal and in the same phase as the color burst.The companion paper discusses how the phase is calculated[4].Since our sampling fre-quency is4times the color sub-carrier frequency,the sine wave has4samples for each period.The cosine wave is the sine wave offset by one sample.Steps6and7demodulate the chrominance compo-nents using the computed sine wave.The LPF3ﬁlter is a16-tap FIRﬁlter.Step8performs the inverse color-space transform to obtain the primary color components.Colors are clipped to the range0to31.Step9computes the bitmap that is displayable on our LCD.It packs the colors into lower15bits of a16 bit pixel.VIII.P ERFORMANCE ANALYSISWe compiled an ANSI C implementation of the sequential decoding algorithm using the Sandblaster compiler and proﬁled it on the simulator.Video de-coding takes25516thread cycles per line.The data used in the implementation amounts to just under 20kB.Thus we may allocate L1memory and there will be no penalty for memory access misses.Note that to write data into an external LCD frame buffer may take additional cycles that must be ac-counted for.We have measured that in the presence of LCD refresh,the DSP cores can store at about 40MB/sec.This is not the feature of the processor design,but rather of the speciﬁc development board. If we display lines at quarter-VGA(320×240)reso-lution,then each line consists320pixels or640bytes. It takes1200thread cycles to copy one line.Step1in the algorithm takes negligible time.All other steps take time proportional to the number of samples decoded.Fortunately,steps2through9are embarrassingly parallel and we can parallelize the al-gorithm with little synchronization overhead.In order to determine the number of threads re-quired,observe that video lines arrive at the rate of 525×30per second.The duration of each line is 1/(525×30)seconds or75×106/(525×30)= 4761.9cycles.While it is acceptable to buffer a few lines for processing,our implementation should be able to decode and display a line every4761.9cycles. If we split video decoding among T threads,then the time to decode a line is(computation+memory copy):25516/T+1200≤4761.9(1) This gives us the lower bound on the number of threads required:T≥7.16(2)Since T must be an integer,the lower bound on the number of threads is8.Decoding every line for a quarter VGA display is overkill.We only have to de-code every other line.This gives as the following, relaxed,bound on T:25516/T+1200≤2×4761.9(3)T≥3.06(4)This indicates that we should be able toﬁt our de-coder into4threads,even accounting for paralleliza-tion overhead.We summarize all the calculations in the following table:Speed of each thread75MHzCost of the sequentialalgorithm25516cyclesTime to copy a QVGAline to the frame buffer1200cyclesDeadline4761.9cycles perlineLower bound on thenumber of threads forQVGA resolutionT≥3.06IX.PARALLEL IMPLEMENTATIONThe parallel implementation is outlined below: DriverThread{Perform line/frame synchronization Forever{copy the next line from A2D bufferperform DLL trackingadjust read positionenqueue the line to video team }}VideoTeamThread(int thread index){ if(thread index==0){dequeue next line;}barrier();run parallel decodingbarrier();}The work is partitioned between one driver thread and T video threads.The driver thread copies datafrom the A/D buffer(in L2)into fast L1memory.The Sandblaster RTOS includes an API that abstracts a circular buffer as an inﬁnite stream with a movable read position.The read position can be advanced or retarded.This is useful in implementing DLL track-ing.In this case DLL tracking involvesﬁnding the start of the sync-tip and adjusting the read position of the A/D stream.This is necessary to adjust for fre-quency offset between the A/D converter and the sig-nal source.This DLL tracking requires little compu-tation.Afterwards the driver thread queues up the line for processing by video threads.The queue,in fact,implements double buffer-ing between the driver and the video threads.The queue is implemented using a common circular buffer algorithm.The circular buffer has three slots. This data structure helps implement concurrent pro-ducer/consumer computations.If there is only one producer and only one consumer,then no additional synchronization mechanism is required to maintain the queue in consistent state.After the initial barrier,each thread runs the steps of the sequential algorithm applied to a quarter of the data.Additional barriers are necessary due to over-laps required by theﬁlters.We use light-weight spin barriers[8].They have very low overhead.In our implementation all processing is done on core1.Thread0is the driver thread.Threads1, 3,5,and7are video threads.Since video threads share data,we spread the intermediate arrays across odd banks.Our current implementation is scaled to full VGA by simply adding another group of4threads.Each group would have an input queue associated with it and the driver thread would round-robin lines be-tween the queues.IX.C ONCLUSIONSWe have presented the implementation of NTSC analog TV on the Sandblaster SDR platform.The implementation runs in real-time and requires only4 threads to perform video decoding for QVGA resolu-tion.Together with the driver thread this amounts to about15.6%of the available computational power of the four-core processor.The other TV protocols:PAL and SECAM differ only in minor details from NTSC and can reuse the same RF front-end.Our work demonstrates that a multi-protocol TV receiver can be added to a conver-gence device at little cost.R EFERENCES[1]Sandbridge Technologies Inc.,TheSandblaster R Convergence Platform, /documents/sandbridge white paper2005.pdf.[2]J.Glossner,D.Iancu,J.Lu,E.Hokenek,and M.Moudg-ill,“A software deﬁned communications baseband design,”IEEE Communications Magazine,vol.41,no.1,pp.120–128,January2003.[3]J.Glossner,T.Raja,E.Hokenek,and M.Moudgill,“A mul-tithreaded processor architecture for SDR,”Proceedings of the Korean Institute of Communication Sciences,vol.19,no.11,pp.70–84,November2002.[4]H.Ye,D.Iancu,J.Glossner,V.Kotlyar,and A.Iancu,“Sig-nal processing algorithms for DSP implementation of analog tv reeivers,”in Proceedings of the31st International Confer-ence on Acoustics,Speech,and Signal Processing(ICASSP), to apprear in2006.[5]Vladimir Kotlyar and Mayan Moudgill,“Detecting over-ﬂow detection,”in CODES+ISSS’04:Proceedings of the2nd IEEE/ACM/IFIP international conference on Hard-ware/software codesign and system synthesis,New York, NY,USA,2004,pp.36–41,ACM Press.[6]NTSC TV Tutotial,.[7]ITU,Recommendation RBT.470-4.Television systems.[8]John M.Mellor-Crummey and Michael L.Scott,“Algo-rithms for scalable synchronization on shared-memory mul-tiprocessors,”ACM put.Syst.,vol.9,no.1,pp.21–65,1991.。