Logic trainer finds
Billy.Pettit at wdc.com
Mon Aug 20 16:32:18 CDT 2007
William Donzelli wrote:
A double-header hamfest weekend yielded a couple of vintage digital
logic trainer items. The first is one of those little wood boxes DEC
Logic labs, but who cares about that. The more interesting thing is a
book for the CDC logic trainer. From the pictures and writeups in the
manual, this box has no logic of its own, but is made to accept a
small number (20) of logic cards from a 1604. It mentions that it can
be lightly modified to take 3000 series cards as well.
Can Billy or Chuck add any comments? I have never seen or even heard
of this box before.
The logic trainer was developed by Control Data Institute. They also did a
workbook with a series of simple experiments. It was a part of their
program to take high school graduates to computer technicians in 12 months.
Lots of government funding for the 12 month program, so the classes were
usually full. I believe there a couple of list members who took that class.
The 1604 and 3000 cards both use +/- 20 volts, though on different pins.
1604 has power on pins 13,14 15; 3000 has power on pins 6, 7 and 8. So the
mod was moving power pins. The signal levels could be mixed without level
converters, though you stressed the 3000 inputs doing it. I only know of
piece of equipment that actually mixed the logic families on the same
chassis: The Digigraphics system. The power wires are always solid red,
blue with black for ground.
I may still have some of the documentation for it, but very uncertain. It's
been a few years. However, Al has posted some of the CDI training manuals
used with it. One is at CDC/modules/60238500_3000pcbs_Dec68.pdf.
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