Warren’s Crazy Small CPU

(c) 2017 Warren Toomey, GPL3

This is the website for version 2 of my “crazy small CPU”, one that has the fewest 7400-style chips. The design has only eleven chips:

The CPU is small enough that you can build it on two breadboards, but it is powerful enough to calculate the Fibonacci sequence up to 27 decimal digits, and to draw a sine wave using Minsky’s circle drawing algorithm.


Version 1: A reg connected to the multiplexer, B directly to data bus
Version 1a: B reg also connected to the multiplexer
Version 2: Asel also connected to the ALU, giving 16 ALU operations


If you want to leave comments about the CPU, feel free to use the GitHub issues page for this purpose.

Here is a video of version 1 of the CPU running the Fibonacci + Minsky sine wave programs in Logisim.

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Note: The ring is chartered for projects that include a home-built CPU. It can emulate a commercial part, that′s OK. But actually using that commercial CPU doesn′t rate. Likewise, the project must have been at least partially built: pure paper designs don′t rate either. It can be built using any technology you like, from relays to FPGAs.