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Symbolic Microinstructions

Symbols and Binary Code For Microinstruction Fields

 

 

 

 

It is possible to create a symbolic language for microcode that is machine-translatable to binary code.

Each line define a symbolic microinstruction with each column defining one of five fields:

Label - Either blank or a name followed by a colon (indicates a potential branch)

Microoperations - One, Two, Three Symbols, separated by commas (indicates that the microoperation being performed)

CD - Either U, I, S or Z (indicates condition)

BR - One of four two-bit numbers

AD - A Symbolic Address, NEXT (address), RET, MAP (both of these last two converted to zeros by the assembler) (indicates the address of the next microinstruction)

We will use the pseudoinstruction ORG to define the first instruction (or origin) of a microprogram, e.g., ORG 64 begins at 1000000.

 




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Computer Instructions | Control Unit Design

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