Control bits for input of A register

[learning67]

I was initially applying the logic that the And of the i-bit and d1 bit is used as the select line for Mux that gives the input to the A register.
But this fails when I want to perform A=A+1 because the i bit=1 d1 bit=1 and it loads the instruction when it should load the value after execution into the A register.
How do I approach this problem? Any help provided will be great!

[cadet1620]

learning67 wrote

I was initially applying the logic that the And of the i-bit and d1 bit is used as the select line for Mux that gives the input to the A register.
But this fails when I want to perform A=A+1 because the i bit=1 d1 bit=1 and it loads the instruction when it should load the value after execution into the A register.
How do I approach this problem? Any help provided will be great!

This Mux selects the data source for the two types of instructions that load values into the A register.

A-instructions load the instruction itself into the A register, and C-instructions with d1=1 load the ALU output into A.

Think about this:

Does it matter what the Mux selects during C-instructions with d1=0?
When must the input to the A register not be the ALU output?

--Mark

[learning67]

Thank you the hints helped a lot!

Built the computer :D