simple Sytems (was:186 (was: CompuGraphics Question))

From: John Honniball <>
Date: Wed Aug 11 07:01:34 1999

On Tue, 10 Aug 1999 21:15:37 +0100 (BST) Tony Duell
<> wrote:
> The System 1 was 2 Eurocards. One of them contained a 6502, 8154 RAM/IO
> (with an optional second one), 1K of RAM, and a monitor ROM. The other
> contained a hex keypad, 7 segment display, and a cassette interface.
> Together they formed a minimal 6502 development system.

This was the first computer I ever built (from a kit). It
was back at school, in about 1978, when I was electronics
lab technician. As you say, two Eurocards, one for
CPU/ROM/RAM and the other for the keyboard, display and (I
think) the cassette interface. The LED display was the
multiplexed type, as used in calculators of the time.

> The System 2 was in a rack. It used the same boards as the System 1,
> although the keyboard/display were left off (the second board was just
> the cassette interface). There was another card which contained a 40
> column text-only VDU and one with more ROM/RAM on it. There was also a
> full QWERTY keyboard which (IIRC) plugged into one of the 8154 ports on
> the CPU board.

I have a rack-mounted Acorn System Three, which has the
disk, full keyboard, VDU and a power supply. I've also
got spares (like EPROMs) and a little documentation.

> These machines are not that common, even in the UK, so they're worth
> saving if you ever see any. A few weeks back I spotted a totally bare
> Eurocard in a local electronics shop. I believe it to be a sound card for
> an Acorn System (although there are no markings on it at all...). One of
> the puzzles for the next few months is to work out what all the
> components should be (there is no silkscreen at all) and assemble it.

Are there any part numbers or markings? I can compare it
with my system, which certainly has an optocoupled parallel
I/O card, and may have a sound card.

> -tony

John Honniball
University of the West of England
Received on Wed Aug 11 1999 - 07:01:34 BST

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