So for my semester project in my 11th grade electronics course, I decided to build a processor! It is a single core processor built up from logic gates, decoders, flip-flops, ROM, RAM, etc. It has 8-bit capability, but it isn't completely finished. As now now, I've only programmed 1 opcode (stor #,reg), but thats because once the hardware is down, programming that is easy . . The real problem I have (besides my MC6845 not working for the CRT display) is that I don't have any arithmetic at all. No ALU. And I can't find any 8 bit ALU's, only the 4-bit LS181. I was thinking of putting two of those together, but I don't know much about combining them and there aren't resources that show that specifically. (I also need to get this done by the end of the school year -_-).
Regarding the processor, here are some pics.
https://i26.tinypic.com/6707xd.jpg
https://i28.tinypic.com/2hxr47l.jpg
This is how I've been testing what vals are in the registers . .
https://i31.tinypic.com/14kbj36.jpg
Stor 2,0100;
Stor 1,0200;
https://i27.tinypic.com/14j3vc1.jpg
And here is a picture of my register bank (synonymous to a cache?)
https://i28.tinypic.com/2zfo3zn.jpg
Sorry for not labeling the chips in the last picture. I'll make sure to make a better diagram later on. But basically, COLUMN of chips on the far right are LS377 octal registers. The next two over are LS244 octal controlled buffers (line drivers?). And in front of those are two decoders, another octal latch, some open collector inverters so I can clear things, etc. The two chips on the lower left are both LS244 so that I can use the register bank's bus as a bidirectional bus. I'll be putting the ALU right under the 3x3 of chips.
Soooooo anyways. Info on the ALU(s)?
Regarding the processor, here are some pics.
https://i26.tinypic.com/6707xd.jpg
https://i28.tinypic.com/2hxr47l.jpg
This is how I've been testing what vals are in the registers . .
https://i31.tinypic.com/14kbj36.jpg
Stor 2,0100;
Stor 1,0200;
https://i27.tinypic.com/14j3vc1.jpg
And here is a picture of my register bank (synonymous to a cache?)
https://i28.tinypic.com/2zfo3zn.jpg
Sorry for not labeling the chips in the last picture. I'll make sure to make a better diagram later on. But basically, COLUMN of chips on the far right are LS377 octal registers. The next two over are LS244 octal controlled buffers (line drivers?). And in front of those are two decoders, another octal latch, some open collector inverters so I can clear things, etc. The two chips on the lower left are both LS244 so that I can use the register bank's bus as a bidirectional bus. I'll be putting the ALU right under the 3x3 of chips.
Soooooo anyways. Info on the ALU(s)?