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 [ 2 posts ] 
 Pathetic Instruction Set Computer 
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Joined: Fri Jan 10, 2014 11:19 pm
Posts: 25
In the "Introduce Yourself" topic, Ed asked:
BigEd wrote:
Hi Brad - it would be great to see any pictures or info you have of that TTL cpu!

As suggested, I am starting a new topic for my reply. "Projects" seemed to be the appropriate forum.

Ed, there's a writeup of the contraption at http://www.bradrodriguez.com/papers/piscedu2.htm . For reasons that will become obvious, I dubbed it the "Pathetic Instruction Set Computer." It has a 16-bit microinstruction, and there is no "macroinstruction" set beyond that. If memory serves, it took 22 TTL chips. Schematics are posted with the writeup. I have a wirewrap prototype around here somewhere; when I succeed in excavating it, I'll take a photo.

Although the article suggested areas for improvement, I think I'll turn the original design into a PCB. It had a certain elegance and simplicity.

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1802, 6809, 8051, 8086, MSP430, Z80 -- there's a Forth for that: http://www.camelforth.com


Wed Feb 19, 2014 6:50 pm WWW

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1632
Thanks for the link to your writeup - I do like the idea of building a viable CPU from scratch.


Wed Feb 19, 2014 9:48 pm
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