* 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.
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.
I got his 6502 kit and worked through his YouTube videos to get it up and running with LCD display and all. I want to actually frame it and get it running, hanging on a wall.
If anyone is new to Ben, find a comfortable chair or couch, make some tea, take a breath, and begin your descent into his long-form breadboard series of nerd-splaining how a CPU works, beginning with basic logic gates.
His follow-on series is a little higher level. He's still at it with the breadboards but he allows that this time the CPU (a 6502) is already built for us. He then walks through how the address bus works, how to attach RAM, etc.
It makes me wish I could be transported back to the 70's when things could still be understood.
I'm still working on ways to add more to the design -- it's been a fun hobby. I actually enjoy cutting the wires and physically putting it together.
See https://archive.org/details/donlancaster_socv1/page/n3/mode/..., https://annas-archive.org/isbndb/9780672217234
Further, these circuits can be directly simulated in an FPGA if you want to teach yourself an HDL like VHDL or Verilog. You really want to learn better and faster ways to organize a CPU, but it's a fun way for a beginner to bridge into this kind of work.
At the local hackerspace, we actually taught a class that assembled a hybrid 8-bit / 16-bit variation of this computer with 1MB of RAM, an 8-bit ALU, a 16-bit data bus / registers, and a 20-bit address bus. With this additional capability, we could program it over serial with a very basic bootloader, and it was powerful enough to compute pi to 1000 digits. Granted, this took about 18 hours, but it could have run faster with a printed circuit board and a crystal oscillator. We just never really got to that point.
As for how powerful such a computer with discrete logic can be, consider that the KB-11A CPU for the PDP-11/45 was built using 74-series logic ICs. It wasn't until after this system that DEC moved on to VSLI. So, this is a way to play with technology found in computers in 1972 / 1973.
As a stepping stone to digital logic and FPGA work, Ben Eater's tutorial isn't bad. Just get yourself a copy of Don Lancaster's TTL Cookbook or CMOS Cookbook to bring his tutorial up to best practices.
Also note that yes it's a computer, but it has 16 bytes of memory to hold both the program and the program's variables.
BYTES. Not KB, not MB, not GB. Bytes.
The demo Fibonacci program is pretty much the most complex thing you can do with it.
But it is in fact a genuine von Neumann computer. And understandable.
For an experience today closer to these machines, you can get a $0.10 CH32V003 microcontroller with 2k RAM and 16k flash.
Here's a 1 Euro retro-computer kit using one that has included in that price support for PS/2 keyboard and VGA video output, all included in the 1 Euro -- even the connectors! All from one 8 pin microcontroller chip:
https://www.olimex.com/Products/Retro-Computers/RVPC/open-so...
But as I understand it the kits are no longer available :-(
The one unavailable part is the fancy wooden box.
Here's my question: Obviously there's tremendous interest in kits like this. Why doesn't Ben or someone else create small company to:
* Modernize the components
* Update the videos
* Add additional modules to make the computer a bit more powerful
(I also made a two-breadboard CPU with ~5 instructions myself but had yet no time to finish the software)
I feel like that could be a good choice for someone doing this today because there's now a kind of a large ecosystem of resources for that design (not that it's inherently better somehow).