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Build an 8-bit computer from scratch (eater.net)
341 points by necrodome on July 30, 2017 | hide | past | web | favorite | 28 comments

I've been following Ben's videos on YouTube ever since he started this project and have been totally transfixed. His approach to building an 8-bit computer on a breadboard has also spawned a bunch of interest from the community.

Just search "my ben eater" on YouTube and you'll find many other people following his steps and making their own computers; some even going as far as to improve upon the original. It's really quite awesome to see.

Hats off to Ben. His succinct videos have done much more for my understanding of low level computing than any computer science professor I've had -- and all through only video.

This is really neat! Also if you want to learn to build a computer from scratch without hardware, just to learn how computers work, The Elements of Computing Systems is a great book to check out. It's used as a text in some CS programs but it is very readable and easy to follow and the software is free and online.


http://www.nand2tetris.org/ is the website for it.

Working through it as we speak. Computer is finished, doing assembler now.

Watching Ben's inspired me to finish my Brainfuck-based CPU designed a few years ago: https://hackaday.io/project/4237-mental-1-a-brainfuck-cpu

Right now it has PS/2 keyboard input, and a 40x2 character display output.

The biggest help was his sensible clock design. I modified it a bit in my design, but the techniques he demonstrates in his videos are incredibly helpful and provide a good base to build off of.

You are insane.

I mean that as a compliment of the highest order. That project is brilliant.

This is amazing, thanks for sharing!

Always love to see these projects because if I had made a clone of myself to to the other work, I'd be doing things like this.

Somewhat surprised that you can still buy LS TTL. I'd have thought it'd be replaced by some 1.5V supply ultraBiCMOSwhatever by now. Or a single die that you program to be whatever last-century TTL function you want, via its WiFi interface...

Time was I has the entire 74xxx series memorized. Long since paged out to make way for more important stuff in my brain.

You can still get pre-LS TTL as well! Gets a bit warm that stuff.

Wow. There wasn't much reason to use that in the 80s once LS and F appeared. Perhaps for Iout(max), which I seem to remember is higher for the non-LS?

Yes fan out is ~25 as opposed to ~10.

Early TTL is still used for building oscillators, timing circuits and monostables because lots of long run products were designed with those in and the LS/HC parts aren't equivalent due to bias current etc.


A Replica 1 is an Apple 1 clone made with permission from Steve Wozniak that people can build from a kit. It is an 8 bit microcomputer with Apple Integer BASIC and optional casette tape interface.

I enjoyed building this computer a lot. But Ben has not yet done a schematic set. so I made my own in kicad and published them https://github.com/kyllikki/eda-designs/tree/master/SAP-BE

The PDF is also there if you do not want to install kicad

I highly recommend Ben Eater's YouTube channel; great video tutorials. He manages to cover a lot in short videos. (Also, consider supporting him on Patreon :)

This would have been so cool as a book! (Any recommendations?) I lack the patience to watch YouTube videos though...

This was so cool as a book. Ben Eater did a fantastic job of making these videos, explaining each concept, but the computer he builds (the SAP, or Simple As Possible) is directly from "Digital Computer Electronics" (c) 1977 by Albert Paul Malvino.

He even goes so far as to mention it and shows a copy of the book in his first video: https://youtu.be/HyznrdDSSGM?t=49

I stumbled across the book 4 years ago when I followed this instructable: http://www.instructables.com/id/How-to-Build-an-8-Bit-Comput...

The instructable is nowhere near as detailed as Ben's videos, but it was all I had at the time, and it recommended that book. Note: when I purchased the book 4 years ago, it was only $5, now I'm seeing it for upwards of $99:


The paperback is only $22, but it lists an additional author not present on the 1977 version, so I don't know if it's the exact same book.

There's the From Nand to Tetris [1] course which has a book. It skips a few steps though. I love Ben Eater's series because it is so thorough. Whenever I'm like "how did x work again" he explains it in detail. If you know most of it by heart it will be slow since it's meant to be able to follow with fairly little prior knowledge of digital electronics.

[1] http://nand2tetris.org

With fairly little, or even with none?

I prefer prose, too, but found these videos to be very good, both in the way they are told and the way he split the content into parts.

For example, he sometimes goes a bit too much into basics such as ones' complement vs two's complement for me, but that's in separate videos, so you can easily skip that.

This is a great step for trusted computing for individuals.

When I saw he wrote his own Assembly language for it...I was then all chips in!

i'd love to see a real "from scratch", that is building your own electronical components ( or something that substitutes, such as the lamp or anything else they used back in the time).

Not sure about home-made integrated circuits or even transistors, but one can definitely make an electronic tube, as shown in this cool video: https://www.youtube.com/watch?v=EzyXMEpq4qw.

I love what you have done here, I cant wait to get some time to try out your "instructions"

I built something like this with the 74 series IC chips when I was in college. It was really fun!

Ah.. this brings back memories. 7400 nand TTL chip with Low power schotky transistors.

Earlier today I looked up that the fastest 74-series are the TI 74AUC line.

Add some nixie tubes, and you have a steampunk wet dream.

Find ye parts:

http://octopart.com http://findchips.com

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