Comment by rs186
Comment by rs186 9 days ago
I did the whole thing, was able to get the Fibonacci numbers appear and learned a lot during the process. However, I would not recommend other people to try this today, because --
* It is not necessarily the best way to spend your time and money. You'll be looking at tens of hours on building it plus over $300 in parts, for a very slow and basic computer that you probably will forget and throw away at some point. Cutting and laying out wires are some of the most tedious and frustrating process. There are other cheaper, more efficient ways to learn how a computer works. It may or may not be worth the effort to you.
* The tutorial is really old, with some very questionable design choices and no updates from the author. Some of the designs are just plain wrong -- e.g. floating inputs or missing resistors. It is very unlikely you can reproduce it by strictly following the tutorial. You'll need to spend time debugging those issues and go to reddit to see other people's experience with this, potentially seeking help as well. No doubt debugging is an important part of designing and understanding the circuit. But only if you have the foundational knowledge and patience, of which I happened to have, but I can imagine that someone who does not understand digital electronics well enough can easily get lost and feel defeated.
* To make the previous point worse, some of the parts are hard to source, depending on where you are. (You'll likely fry or physically break a few components when building it.) Many of the parts are not very commonly used these days, and not exactly easy to acquire, if you only need 1 or 2 of them. I had to go to eBay to get some of them, which took about a week, during which I had to stop and wait for parts to arrive.
With all that said, this may still be the best resource out there that lets you build all these on a breadboard, as I am not aware of an alternative that addresses all the issues above.
I’ll play devil’s advocate.
Following Ben’s videos and building the 8-bit CPU is the first thing that ever helped me “get” electronics and circuitry.
Honestly, way more than half of the fun has been in finding the design flaws and designing fixes for them as well as improving and expanding the design itself.
I have learned so much by going down rabbit holes. The original clock design assumes a make-before-break switch but the one shipped with the kit is the opposite, and this can put one of the flip flops into an invalid state. I switched to CMOS chips and learned why you shouldn’t drive loads like LEDs directly from digital outputs, and dove into the easiest way to power 8 LEDs off 8 IC outs without a mess of transistors. I followed another person’s expansion to a full 8-bit instruction register and a more featureful ALU (with my own changes of course). I worked to minimize power consumption. I’ve learned how to use an oscilloscope. I’ve improved upon nearly every module, and built and rebuilt them all a handful of times.
None of this has any real benefit for the CPU. It will never run anything more than toy programs. But that wasn’t ever the point.
All the flaws in the original design have been perfect as launching points for learning more and more.