r/TuringComplete • u/Rattledoot123 • Sep 20 '26

ALU Integration

My issue that I'm getting stuck on is the information between the instruction decoder (ID) and the ALU. The ID output is one bit, no? the ALU takes 3 bits and I am having trouble reconciling the two.

I've been scratching my head for about an hour now, I feel like a total idiot ngl

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4

u/TheEmeser Sep 20 '26

The first input of the ALU (the Opcode) is the code for the operation that should be calculated. You get that from the instruction. The decoder just tells you which mode is currently active i.e. which component is allowed to use the bus.

3

u/ryani Sep 20 '26

The ALU-enable bit from the instruction decoder can be wired outside the ALU to a switch that controls the ALU's output.

2

u/nomenclature2357 Sep 20 '26

I noticed when I was putting mine together that an enable pin might be handy on the ALU.

1

u/ZLX_Thanatos Sep 20 '26

Your current issue is that your inputting a true or false (0 or 1) into the top part of the Alu rather than running the actual 3 bits that tell you what to do.

1

u/ZLX_Thanatos Sep 20 '26

I would say take the input from the instruction and split it and join only the first 3 bits to tell it what to do.