Why?

 

Welcome to AAC!

Could you post some context and your answer?

 

So I have this diagram, and I need to determine whether or not the program counter needs a write-enable control:

 

Depends on details you haven't shown. Every architecture has it's own needs. If we try to answer we are making assumptions about a few things because we lack the context.

Besides, YOU need to make YOUR best attempt at answering and explaining that question. That will also help establish the needed context.

 

A write enable control would allow the contents to be altered to implement a branch or a call instruction. Since the incrementing is done with an adder how else are you going to advance the Program Counter if you don't have a write enable?

 

A write enable control would allow the contents to be altered to implement a branch or a call instruction. Since the incrementing is done with an adder how else are you going to advance the Program Counter if you don't have a write enable?

The crux of the question is whether the write enable needs to be controlled, versus just tying it so that it is permanently enabled.

 

Since the incrementing is done with an adder how else are you going to advance the Program Counter if you don't have a write enable?

good point.
When will you not need a write? It seems to me that every instruction you will increment or load new address and never will you do nothing. So if you had a enable/disable pin it would always be in the write position.

 

good point.
When will you not need a write? It seems to me that every instruction you will increment or load new address and never will you do nothing. So if you had a enable/disable pin it would always be in the write position.

Let's let the TS think about HIS homework problem and offer something up.