
MyCPU – Homebrew Computer from Discrete Logic Gates - bane
http://mycpu.thtec.org/www-mycpu-eu/index1.htm
======
e19293001
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/](http://www.homebrewcpu.com/)

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

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

------
bane
Here's somebody's build of this.
[https://imgur.com/a/rUnNb#0](https://imgur.com/a/rUnNb#0)

------
dennis-mycpu
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

~~~
e19293001
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](http://www.homebrewcpu.com/construction.htm)
(timeline section)

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

------
kens
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.)

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

~~~
loup-vaillant
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?

~~~
jacquesm
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.

~~~
loup-vaillant
This guy
[http://www.megaprocessor.com/homebrew.html](http://www.megaprocessor.com/homebrew.html)
may eventually find out.

~~~
jacquesm
That's absolutely amazing.

[http://www.megaprocessor.com/index.html](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.

------
geocrasher
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](http://mycpu.thtec.org/www-mycpu-eu/index1.htm))

~~~
chmullig
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](http://mycpu.thtec.org/www-mycpu-eu/index1.htm)

~~~
dang
Ok, we changed to that from [http://www.mycpu.eu/](http://www.mycpu.eu/).

