449 original code, complement code, inverse code

Original code 、 Complement code 、 Inverse code

• The bottom layer of the computer uses binary numbers to store data , But when a computer stores a number, it does not directly store the binary number corresponding to the number , Instead, store the number The complement of the corresponding binary digit .

So next we need to know the original code 、 Inverse and complement .

1、 Number of machines

Number of machines ：

• a number The storage form in computer is binary number , We call these binary numbers Number of machines ;
• Machine numbers are signed , Using machines in a computer The highest bit holds the sign bit ,0 It means a positive number ,1 A negative number .

The true number of machines ：

• Because there are sign bits , So the formal value of machine number is not equal to its true value ;
• In terms of the number of machines 1000 0111 For example , Its real value is -7, And the formal value is 135.
• The true value of the signed machine number is called the true value of the machine number .

2、 Original code

The representation of the original code is the same as that of the true value of the machine number , That is to say, the symbol is represented by the first digit , The rest of the bits represent values , For example, the positive and negative of decimal 1, use 8 The original code of bit binary is as follows ：

【+1】= primary ：[ 0000 0001 ]

【-1】= primary ：[ 1000 0001 ]

2、 Inverse code

The inverse code is expressed as ：

• Positive numbers </