TTL homebrew CPUs

Lars Hamren hamren at
Sat Jul 7 14:38:15 CDT 2007

The first computer built by Computer Automation, circa 1967, was the
PDC 808. It was an 8-bit TTL-only machine with a very basic
instruction set. In "Computer Technician's Handbook" Brice Ward
describes tat machine in great detail. Should be enough to build a
replica from.

A scanned version of the relevant parts of that book is available from

PDC stands for Programmable Digital Controller. The word "computer"
was avoided because people were afraid of them!

The "8" means 8 uS cycle time, and "08" means 8 bits. The 208 was
three times as fast (2.66 uS cycle time, hence the "2").

Lars Hamrén              Tel...: +46( 46)189090
Svensk Datorutveckling   Mobile: +46(705)189090
Vadmöllan 211            e-mail: hamren at
S-225 94 Lund            WWW...:

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