Original code, inverse code, complement code
There are three representations of signed numbers in computers, namely, original code, inverse code and complement code
The three representations are different.
Original code: directly translate binary into binary in the form of positive and negative numbers
Inverse code: the sign bit of the original code remains unchanged, and the other bits are reversed
Complement: inverse code + 1
The original code of a positive number is the same as the complement of the inverse code
Large and small end introduction
Large end (storage) mode: the low bit of data is saved in the high address of memory, and the high bit of data is saved in the low address of memory
Small end (storage) mode: the low order of data is saved in the low address of memory, and the high order of data is saved in the high address of memory
Why should there be large and small ends?
In the computer system, taking bytes as the unit, each address unit corresponds to a byte, and one byte is 8bit. For processors with more than 8 bits, there must be a problem of how to arrange multiple bytes because the register width is greater than one byte. Therefore, it leads to large end storage mode and small end storage mode.