How can I add NOR to the ALU

[kingpinzs]

I was thinking to add another bit to the f but I am not sure if that would be the best thing or can the ALU already do NOR in some combination it already has?

I did add look ahead carry to my ALU and over flow detection. The ALU test that was given and now I am adding a test for the over flow even though I did verify it manually. The over flow detection is built into the adder.

It can be seen here wit hall the updates and progress.
http://diycs.blogspot.com/

[cadet1620]

Since the ALU can independently invert the inputs and output of the AND operation various combinations of nx, ny and no with f=0 will compute NAND and NOR, similar to how OR is computed. Remember how you built your OR gate in HDL.

--Mark

[kingpinzs]

With that and SLT set less than function then it would be a basic MIPS ISA ALU.

When the ISA  says it needs the NOR and SLT functions. Does that means in any way it can be obtained in hardware?

[cadet1620]

I'm not sure I understant the question you are asking. The Hack ALU can't calculate SLT as described in the MIPS ISA; you would need to modify the ALU design to add that function.

--Mark

[kingpinzs]

I have been looking all over the web for a good description on how STL works. Do you have any advice on this?