What are Logic Micro-Operations in Computer Architecture?

Logic operations are binary micro-operations implemented on the bits saved in the registers. These operations treated each bit independently and create them as binary variables.

For example, the exclusive-OR micro-operation with the contents of two registers R1 and R2 is denoted by the statement

P: R1←R1$\oplus$R2

It determines a logic micro-operation to be implemented on the single bits of the registers supported that the control variable P = 1. Consider that each register has four bits. Let the content of R1 be 1010 and the content of R2 be 1100.

The exclusive-OR micro-operation stated above represent the following logic computation −

1010   Content of R1
1100   Content of R2
0110   Content of R1 after P = 1

The content of R1, after the implementation of the micro-operation, is similar to the bit-by-bit exclusive-OR operation on pairs of bits in R2 and previous values of R1.

Special Symbols

Special symbols will be approved for the logic micro-operations OR, AND, and complement, to categorize them from the matching symbols that can define Boolean functions. The symbol V can indicate an OR micro-operation and the symbol can indicate an AND micro-operation.

The complement micro-operation is similar to the 1's complement and supports a bar on the highest of the symbol that indicates the registered name. There are various symbols, and it will be applicable to differentiate between a logic micro-operation and a control (or Boolean) function.

There is another sense for supporting two sets of symbols can that recognize the symbol +, when can symbolize arithmetic plus, from a logic OR operation. Although the + symbol has two meanings, it will be available to determine between them by observing where the symbol appears.

When the symbol + appears in a micro-operation, it will indicate an arithmetic plus. When it appears in a control (or Boolean) function, it will indicate an OR operation. We cannot use it to symbolize an OR micro-operation.

For example, in the statement

P+Q: R1←R2+R3,R 4←R5V R6

The + between P and Q is an OR operation between two binary variables of a control function. The + between R2 and R3 determines an add micro-operation. The OR micro-operation is named by the symbol V between registers R5 and R6.

Updated on: 24-Jul-2021

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