I find hardware and electronics pretty interesting. So when I was looking around on the internet and saw a link to a home built CPU, I just had to click! A fellow named Jim has made a complete CPU, called the Magic-1, out of just 74xx series of circuits. If you haven’t used or know what 74xx series circuits are, take a look at the picture. These chips were very popular back in the day, as in, a few decades ago. Today there are faster and more powerful chips available. But because Jim used the 74xx series of chips, he was able to get much more control and learn a lot about CPU design.
I personally found Jim’s work so interesting because I have been toying around with designing a somewhat useful CPU myself, since I took a class on digital design. In that class, we built a simple computer that had 1 register, 4 bit (not byte) address and data bus, and only 7 instructions. It was an interesting exercise and very educational, but it couldn’t really do anything other than add small numbers together. I have made a few attempts at starting a design, but I usually got hung up on finding a balance between instruction set power, complexity, and size. It would be nice to be able to perform 32 bit vector math with all arguments in the instruction, but thats just not realistic for me at this point.
Seeing Jim’s work is pretty inspirational; maybe this semester I’ll get off my butt and start to work on my own computer. However, I don’t think I will use 74xx chips. FPGAs are very powerful tools, and since I’ve been using them for my research, I figure they will be the perfect way to start any work. I think the biggest thing is to just get started and stop thinking about starting.
P.S. Another interesting point of note is that Konrad Zuse, a German engineer, had built his own computer during World War 2, but instead of an electric clock, he used a crank as the clock! Pretty neat!