In reply to this post by Samba - linux mailing list
On 26/09/17 22:02, steve jenkin via linux wrote:
> Warren Toomey used to teach at ADFA, will be familiar to some of you.
> He’s built an 11-chip design with "7400-style chips” (and 1kbit RAM and some ROM)
> I didn’t know that ‘this was a thing’ until tonight.
> Seems there’s a whole community in this "Homebuilt CPUs WebRing”.
> Steve Jenkin, IT Systems and Design
I'm partway through building one entirely out of bipolar (and,
possibly in the future, Field-Effect) transistors:
The 512-bit ROM and 8-byte RAM cards are real, but not fully tested
yet. I am trying to determine how fast I can clock them. (Each RAM
bit needs 6 transistors to be able to store a bit, read it and to
change it, so lots of transistors just for 8 bytes...).
My first aim is to build a CPU that can run BF programs. Will need
quite a few 8-byte RAM boards for that...
My design is intended to be fully transparent - any signal can be
probed at any time to ensure it is not "hidden". So, no ICs... Also,
fully static, so the thing can be stopped at any point and inspected
with no loss of data.
Started working on it over 5 years ago - maybe I'll finish it one day
This reminds me of how I got into computers in the first place.
In 1974/75 I was going through radio school in the RAAF and had been interested in
electronics all through high school. During that time Electronics Australia published a
project called the EDUC-8. (https://en.wikipedia.org/wiki/EDUC-8). It was very primitive.
I had planned to build one but never did. What I did to was chase through the
documentation and schematics until I had a good understanding of how it worked.