8 bit computer, microcode challenges My 8 bit instructions can have up to 8 microcode steps each; I defined up to 24 control signals (thus needing 3 bytes per step); So in the Arduino Nano I’m using, I have to
8 bit computer, output module, problem solved
8 bit computer, output module, problem solved Remember that annoying problem I spoke of? I solved it! It appears I had soldered two connections together by accident. Almost invisible, but still two outputs were connected, resulting in double displays on
8 bit computer, instructions and microcode
8 bit computer, instructions and microcode When designing and building your own computer, you have to design and build your own instruction set as well. So that’s one of the things I’m doing right now. One of the functions of
8 bit computer, buildup status
8 bit computer, buildup status The status so far in pictures:
8 bit computer, output module, annoying problem
8 bit computer, output module, annoying problem As you can see in the picture on the right, the output displays two little ‘-‘ signs – and sometimes even more segments – in a dim, lightly flickering way, to the left
8 bit computer, Output Module complete
8 bit computer, Output Module complete Today I finished building and testing the Output Module for my 8 bit computer. See video and picture below.
8 bit computer, test the Output Module
8 bit computer, test the Output Module Today I hooked up my Output module – still on breadboard – to the signals from the PCB modules. As you can see in the video below, it works so far. At first,
16 position rotary switch for hex input
16 position rotary switch for hex input Found this post for a better input possibility:
8 bit computer, ALU complete
8 bit computer, ALU complete Everything is connected now on the ALU board. the bus has been connected (blue wires) the A register is connected to the ALU chips (purple wires) the B register is connected to the ALU chips
8 bit computer, building up the ALU
8 bit computer, building up the ALU The ALU Building up the heart of the computer, the two big chips are 74LS181’s (4 bit ALU’s, hence there’s two of them). The two little chips below them are the 74LS245 tri-state