MyCPU – Homebrew Computer from Discrete Logic Gates | Hacker News Reader

MyCPU – Homebrew Computer from Discrete Logic Gates

mycpu.thtec.org

69 pointsbane14 comments

This project was inspired by Magic-1[0]. The construction is entertaining to read[1]. And it is used currently as a web server[2]. What a very fantastic project!

Quoting from the project history:

In the beginning....

Magic-1 really began during a lunchtime discussion with Ken Sumrall at Vito's Pizza in Sunnyvale, CA sometime in the Spring of 2001. I was complaining to Ken about how as a compiler writer I was woefully ignorant about how CPU hardware really worked. I hadn't taken any electronics classes in college, and was only vaguely aware of what transistors, resistors and capacitors were. Ken recalled an old series of magazine articles by Forrest Mims on building a very simple CPU from TTL parts, and suggested I read it. Over the next few weeks, I tracked down those articles, as well as Mims' "Understanding Digital Computers" and a textbook by Albert Paul Malvino, "Digital Computer Electronics."

I read them all, and when I next had lunch with Ken at Vito's I reported back that it all seemed much clearer now - so much so that I thought I could even build a CPU myself. Then Ken said, "well, why don't you?".

Why not, indeed?

And so the Magic-1 project began.

[0] - http://www.homebrewcpu.com/

[1] - http://www.homebrewcpu.com/construction.htm

[2] - http://www.magic-1.org/

Here's somebody's build of this. https://imgur.com/a/rUnNb#0

Some clarification: The MyCPU was not inspired by Magic-1. It is a completely parallel development. It is very difficult to say which CPU was first. - Dennis, the developer of MyCPU, www.mycpu.eu

Sorry about that. I couldn't edit my post anymore. I've searched about the starting date of Magic-1 and MyCPU:

Magic-1 - December 6, 2001[0]

MyCPU - February 2001[1]

Therefore, MyCPU was started first although the completion appears to be difficult to determine.

Thank you for bringing this up Dennis.

[0] http://www.homebrewcpu.com/construction.htm (timeline section)

[1] http://mycpu.selfhost.it/epj03.htm (About the history of MyCPU)

Pretty cool, but it isn't made from discrete logic gates. It's built from MSI TTL chips that contain a bunch of gates. And the ALU is a table lookup using two 1 megabyte ROMs. (Reminiscent of the old IBM 1620 which used a table lookup in core memory for arithmetic.)

Would 'Homebrew Computer from 74HC* series except eprom, RAM and UARTs' work better for you?

Personally, I don't mind RAM. That's a given, even on an 8 bit computer, and a bigger RAM doesn't invalidate the rest.

Look up table arithmetic on the other hand feels more like cheating: it makes multiplication as easy as bitwise XOR, and that kinda destroys my "retro" feel. Great choice however if the ALU bores you.

Me, I'd lean towards a different kind of cheating: programmable chips such as the 22V10. Because of reasons. The "22V10 computer", how would that sound?

Hm, makes you wonder if you built an 8 bit computer entirely out of discrete components (transistors, resistors, diodes) how large it would be, and what clock you could still attain. Power usage would probably be pretty impressive too.

This guy http://www.megaprocessor.com/homebrew.html may eventually find out.

That's absolutely amazing.

http://www.megaprocessor.com/index.html

I saw the thread on HN when it passed (even commented on it) and then promptly forgot. Thanks for the reminder.

Website looks to be down or at least very slow due to load. Should move the DNS to CloudFlare and host it there- it will help a lot in cases like this.

(I was going to make a joke about how maybe hosting the site on the MyCPU was a bad idea, but thought that perhaps that was a silly notion. It isn't. The site itself notes that it is hosted on the MyCPU computer, and gives this alternate address if the site is slow: http://mycpu.thtec.org/www-mycpu-eu/index1.htm)

That link is to the version hosted on a MyCPU. There's a bar at the bottom advertising a backup: http://mycpu.thtec.org/www-mycpu-eu/index1.htm

Indeed- I saw the same after it finally loaded, and modified my comment accordingly.

Ok, we changed to that from http://www.mycpu.eu/.

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