Register to reply

Microinstruction and microoperation

by RobikShrestha
Tags: microinstruction, microoperation
Share this thread:
RobikShrestha
#1
Mar27-11, 07:27 AM
P: 26
When we write machine level code of say,
add a,b
Then the CPU does many things,
I am confused, whether microinstruction is the set of all the control signals generated by the control unit i.e. is microinstruction = control unit's equivalent set of signals for add a,b as a whole? or is it just one set of control signals such that many microinstructions would be necessary to perform add a,b?
Phys.Org News Partner Science news on Phys.org
What lit up the universe?
Sheepdogs use just two simple rules to round up large herds of sheep
Animals first flex their muscles
Bill Simpson
#2
Mar28-11, 02:14 PM
P: 1,037
What a microinstruction consists of will depend on the architecture of the processor. Usually I would think most microcoded architectures would use several microinstructions to implement each machine instruction, say "gate a,b to the ALU" followed by "gate the sum from the ALU to the destination and update the status" and "increment program counter and gate to memory to fetch next machine instruction."

If all control signals needed to execute each machine instruction could be encoded into a single wide word and executed at once then perhaps the idea of using microinstructions would be replaced by hard wired CPU control with no microinstructions.


Register to reply