Art of Assembly Language, 1st Edition

2.8. 2.8 Logical Operations on Binary Numbers and Bit Strings

The previous section defines the logical functions for single bit operands. Because the 80×86 uses groups of 8, 16, or 32 bits, we need to extend the definition of these functions to deal with more than 2 bits. Logical functions on the 80×86 operate on a bit-by-bit (or bitwise) basis. Given two values, these functions operate on bit zero producing bit zero of the result. They operate on bit one of the input values producing bit one of the result, and so on. For example, if you want to compute the logical AND of the following two 8-bit numbers, you would perform the logical AND operation on each column independently of the others:

%1011_0101
                 %1110_1110
                 ----------
                 %1010_0100

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