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 Some Minimal Instruction Set CPUs 
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Joined: Mon Oct 07, 2019 2:41 am
Posts: 273
Nov 1977 Byte Mag, has "Build a computer from scratch".
It is a 8 bitter, 4 instructions In,Add,Store(negitive),Jump if Postitive.
Ben.


Last edited by BigEd on Fri Nov 13, 2020 10:45 am, edited 1 time in total.

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Fri Nov 13, 2020 10:29 am

Joined: Tue Dec 18, 2018 11:25 am
Posts: 40
Location: Hampshire, UK.
https://archive.org/details/byte-magazine-1977-11/page/n78/mode/1up

It is a very minimal instruction set, but neatly tackles the bootstrap problem with its WIO instruction.
Code:
”WIO    00xxxxxx    Wait for input to location N.  Display current contents of location N while waiting.”

Although entering a program by this method would be a little tedious, it seems good enough for entering a small secondary bootstrap.

It is very similar to the method used in the CARDIAC paper computer.
https://www.cs.drexel.edu/~bls96/museum/cardiac.html


Fri Nov 13, 2020 11:02 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1647
I've a feeling the 1802 similarly supports a front panel bootstrap


Fri Nov 13, 2020 12:04 pm

Joined: Mon Aug 14, 2017 8:23 am
Posts: 157
Nice to see a bit of home-built TTL computing history.

However it had a chip-count of 35 ICs, of which 8 were the RAM.

The instruction set was very minimal - leaving a lot of scope for future improvements.

I would have thought that using a pair of 74181s as the ALU would have encouraged a more diverse instruction set.

In the author's defense - it was his first electronic project, and he learnt a lot about TTL design from the exercise - and he got an article published in BYTE !


Last edited by monsonite on Thu Apr 01, 2021 11:51 am, edited 1 time in total.



Fri Nov 13, 2020 12:32 pm

Joined: Tue Dec 18, 2018 11:25 am
Posts: 40
Location: Hampshire, UK.
Dr Jefyll’s MISC gets another mention on Hackaday.
https://hackaday.com/2021/03/31/one-bit-cpu-runs-at-a-blistering-60hz/


Thu Apr 01, 2021 10:04 am

Joined: Mon Oct 07, 2019 2:41 am
Posts: 273
Turing Machine's while not practical, could also be considered one, depending on you view the state table
and tape memory. They also look nice in mechanical form.
Wooden
https://hackaday.com/2018/03/08/mechani ... g-machine/
https://www.youtube.com/watch?v=vo8izCKHiF0
Taditional
https://www.youtube.com/watch?v=E3keLeMwfHY


Sat Apr 03, 2021 4:58 am
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Joined: Tue Jan 15, 2013 5:43 am
Posts: 186
B.Bibby wrote:
Dr Jefyll’s MISC gets another mention on Hackaday.
Thanks for that, B.Bibby. Sorry I've been slow to notice your post. I need to visit Anycpu.org more often!

Also belonging on the MISC list are three offerings from Myron Plichota:

-- Jeff

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