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.
_________________1802, 6809, 8051, 8086, MSP430, Z80 -- there's a Forth for that:
http://www.camelforth.com