Joe Wingbermuehle's Q2 Computer

Joe Wingbermuehle ( has produced a 12-bit accumulator-architecture computer using discrete N-channel MOSFETs.

The Q2 has simple 8-opcode instruction set (like the PDP-8!), uses a one-bit-serial ALU, and addresses 4096 12-bit words of memory (although a memory expansion mechanism allowing multiple 4096-word “fields” to be latched in can provide more total memory space). The first 128 words of memory form a “zero page” a la the PDP-8 or 6502/65816, and the last address (FFF hex) is appropriated as an I/O address, leaving 3967 words of “regular” memory between the zero page and the I/O port.

Somewhat different information about the Q2 is available on, and everything necessary to replicate the computer seems to be available on GitHub.

(Via the Minimalist Computing group on Facebook.)


Nice. Just to compare, the PDP 8/S had 1001 transistors using DTL gates.
Guessing about 4 diodes per transistor, about 4K diodes.

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Also, a remarkably nice board.

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I recently found it on the web.
Hard to build with that many parts. But very nice is the online sim (link on that site).
That includes some games like Pong, Hunt the Wumpus, Snake, Invaders and Game of Life.
The display consists of just 2 lines. But it’s fun.