数字电路英文版PPT--第二单元讲课教案

§2.1 DECIMAL NUMBERS
You are familiar with the decimal number system because you use decimal numbers every day. Although decimal numbers are commonplace, their weighted structure is often not understood.
Sign bit : The left-most bit of a binary number that designates whether the number is positive (0) or negative (1).
Weight : The value of a digit in a number based on its position in the number.
In this section, the structure of decimal numbers is reviewed. This review will help more easily understand the structure of the binary number system, which is important in computers and digital electronics.
数字电路英文版PPT--第二单元
Weight [ 权 ]
Carry [ 进 位 ]
Remainder [ 余数 ] Quotient [ 商 ]
Integer [ 整数 ] Fraction [ 小数 ]
1’Co百度文库plement [ 反码 ]
2’Complement [ 补码 ]
Format [ 格式 ] Precision [ 精度 ]
BCD : Binary coded decimal; a digital code in which each of the decimal digits, 0 through 9, is represented by group of four bits.
Byte : A group of eight bits.
Mantissa [ 尾数 ]
KEY TERMS
Alphanumeric : Consisting of numerals, letters, and other characters.
ASCII :American Standard Code for Information Interchange; the most widely used alphanumeric code.
Overflow: The condition that occurs when the number of bits in a sum exceeds the number of bits in each of the numbers added.
Parity : In relation to binary codes, the condition of evenness or oddness of the number of 1s in a code group.
In the decimal number system each of the ten digits, 0 through 9, represents a certain quantity.
Stated anther way: A base—10 number system. 3.
EXAMPLE 2-1 Express the number 47 as a sum of the values of each digit.
Mantissa : The magnitude of a floatingpoint number.
Most significant bit (MSB) : The left – most bit in a binary whole number or code.
Octal : Describes a number system with a base of eight.
Hexadecimal : Describes a number system with a base of 16.
Integer : A whole number.
Least significant bit (LSB) : Generally, the right –most bit in a binary whole number or code.
Digit : A symbol used to express a quantity.
Exponent : The part of a floating-point number that represents the number of places that the decimal point is to be moved.
Floating-point number: A number representation based on scientific notation in which the number consists of an exponent and a mantissa.
Gray code : An unweighted digital code characterized by a single bit change between adjacent code number in a sequence.
Carry : The digit generated when the sum of two binary digits exceeds 1.
Complement : The inverse or opposite of a number.
Decimal : Describes a number system with a base of ten.