Simon computer

Jim Beacon jim at
Wed Aug 23 14:22:20 CDT 2006

From: "Marvin Johnston" <marvin at>
> I love the comment about a warning sign for the computer :)! I have a
> sense of humor, and that fits right in :).
> I've had a number of requests for scans of the Simon manual, but the
problem is
> one of copyrights. A number of years ago, someone got copies of the
> from the Babbage Institute but with the restriction they couldn't
distribute it.
> I've never pursued that, but I am certainly aware of it. I've got the
> Radio-Electronics issues, the subsequent reprint and scans of the reprint.
> have a better scanner now, and they need to be rescanned. Also FWIW, the
> Radio-Electronics magazines have color illustrations where they are in B&W
> the reprint. Not much of a problem except the color makes it MUCH easier
> follow, since some of the signals being discussed in the text are
highlighted in
> red, and are not as obvious in the reprint.
> The next question then is what would it be worth to provide a working unit
> similar to the original (would need to use more modern relays, and the
> could be a problem)? Making a simple electronic paper tape reader wouldn't
> hard as there are a number of plans for a manual "pull the tape through by
> designs to read the tape. I would think a PIC would make for a very simple
> cheap design. Personally, I like the idea of seeing a hand wired chassis
> laced wiring, but it certainly would take some time. What about a PC board
> all of the grunt wiring done and laid out for a current relay? What would
be the
> price point at which it might sell?

I've got a scan of the articles, and most of the parts, including a (Creed)
tape reader. I was planning on building mine to run from 50V, as telephone
relays and steppers for 50V are still relatively common over here (and I
have a large box full ready.....). The only difficult part to find was the
tape reader (5 unit, solenoid stepped), and it does need to be stepped by
the machine, as it forms the main storage (effectively ROM). An alternative
would be a simple basic program on a PC, interfacing through the parallel
port, or a PIC. Bear in mind that you need to be able to punch tapes to
program the machine, so for program development, a PC interface is a better
idea (I only have telegraph type 5 unit punches, so I have to provide a
serial signal at 45.45 or 50 Baud to operate the punch - if anyone in the UK
has a 5 unit solenoid type punch that they don't want.....)

the machine is fairly simple, and anyone with patience and basic
metalworking skills should be able to build one from scratch, however, be
warned, the machine was published as an experimental design, and you will
need to fill in one or two gaps in the articles.


More information about the cctalk mailing list