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I am no longer active in this hobby for the foreseeable future. 
I will no longer maintain or update the website, but I will leave it accessible to the web for as long as possible (years).


8080 CPU
6500 Series
6800 CPU

DG Systems
System Cards
Printer A & B
Disk Drives
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Z-80 Processor Board

The Digital Group Z80 card was the first functional computer to use a Z80 chip. This according to one hobbyist newsletter at the time (which I will have to find again and add here!) and confirmed by me with Dr. Robert Suding in conversation, March of 2004. Dr. Suding had a working Z80 system only two days after receiving the first chips, and was demonstrating Z80 based Digital Group computers at the National Computer Conference (June 11th, 1976) in New York City two weeks later (See flyer #7)--one full month before the chips were available for sale. According to the good doctor, "Frederico never had a chance to try out his own product, so each morning before the show opened, I showed him how a Z-80 worked."

The new Z80 board was advertised in Byte Magazine in the August 1976 issue in an ad entitled "Super Chip", and quickly became the most popular processor sold by Digital Group.

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Fully restored Z80 Processor Board (Factory Assembled)


Most of the CPU boards I have acquired were in poor condition, sometimes due to poor assembly techniques or frustrated repair attempts, or often to an accumulation of small modifications poorly done or rushed. Combined with the effects of time, most of my boards require some restoration to make them operate again. Coupled with the fact that DG used the cheapest of the cheap IC sockets available, nearly every board made has intermittent problems that can often be cured only by replacing all of the aging sockets.

Whatever the condition, I never, ever power up any board without a thorough clean up and inspection under a magnifying glass. every board is evaluated carefully to determine the level of restoration needed. Sometimes this is just a good cleaning with minor solder clean up, other times it means a total tear-down and rebuild. If the circuit traces have lost plating or corrosion is visible on the board top side, tear-down is the only way to go.

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Z80 Processor Board, Solder Side

Z80 Information

z80_cpu.pdf - Contains assembly instructions for the Z-80 card with schematics and board layout. See my Documentation page for many more related files.

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Z80 Processor Board, Layout


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Copyright 2008 Bryan's Old Computers
Last modified:
October 16, 2009