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The Blinking Computer lives!

A project log for The Blinking Computer

An educational 8-bit CPU made from < 256 transistors with lots of LEDs that anyone can build and learn from

Tony RobinsonTony Robinson 11/29/2021 at 11:190 Comments

The Blinking Computer never really died, it just ran at 0Hz for a while....

The original design had 5 general purpose registers and used a Raspberry Pi for RAM.   It's sad but true that if your hardware skills are at my level everything has to be very very simple and the 128 bits of storage that the design called for along with some complex instruction sequencing was too much for me.   So I really went down the rabbit hole of storage and simple architectures for a long time.  Also I wrote a ton of code for the old architecture, including a Forth like language, floating point, random numbers, etc and that's now archived on github.

I hope I'm about to emerge from the rabbit hole.   I have a CPU whose only state is the program counter and three flags (carry, zero and negative) which address 32 bytes of RAM.   What's more it only has one sort of instruction, Mi = Mj OP Mk., that is load a couple of bytes, throw them through a simple (1 bit!) ALU and write the result back.  I think this is as simple as it could ever be and still be useful as an educational computer (do leave feedback!).   I've written some notes and even published a spreadsheet which runs simple code.   

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