Brendan's Classic Microcomputer Trainer Kit

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Radio Shack Microcomputer Trainer Kit

The Radio Shack Microcomputer Trainer was one of those old-style "spring-terminal" type kits (such as the 50-in-1 or 250-in-1, both of which I also own), but with a twist. This kit really had only one purpose - to wire up a little microcontroller that had a tiny bit of RAM and a very small instruction set built-in to a clock, LED displays, a keypad, speaker, and, of course, power, which was supplied by six AA batteries.

I have some very fond memories of this little computer, especially while road-tripping in Dad and Mom's big class-A motorhome in the 80s - hey, it was the most powerful portable I had at the time! I would spend hours writing little programs for it while looking out the window of my "room", my top bunk bed at the back of the motorhome. Learning how to use it went hand-in-hand with my limited knowledge of assembly language programming on the Tandy Color Computer 2 (a little Motorola 6809-based machine) at the time.

I soon hope to include some more of my older programs. Until then, the entire 180-page manual, containing info regarding the built-in games and other capabilities and specs is available here.

I have also created a quick reference guide that attempts to collect together information about the architecture, opcodes, and brief descriptions of the built-in programs included on the mask ROM. It can be found here

I was contacted at the beginning of 2011 by Andrew Benoit of New South Wales, Australia, who has successfully one-upped me in terms of a scan of the Microcomputer Trainer manual. You can find his much improved version in PDF format, here. Thanks very much, Andrew! I know how much work this is to scan!

Michael Merrick, of Hermleigh, Texas, contacted me about the repackaging he's done with his kit for use as test equipment. Click on the images below to view the large versions.

This is the original repackage.

New repackage, but with original repackage keypad.

New repackage, with new keypad.

He explained to me that the set of 4 green LEDs at address $5E also run through buffers and control 4 relays inside the box. The terminal bus on the back of the latest repackages are, in turn, controlled by these relays. The jack with the red and white wires on the left of the unit is the 5V power supply to the relay coils.

The label on the front of the box is an old TI calculator label, since the microprocessor in the Microcomputer Trainer is from Texas Instruments.

Under the label is a small speaker.

To the right of the speaker is a switch which allows manual disable of all of the relays.

The red LEDs are at address $5F. Note, also, the original 7-segment LED display to the right.

The perfboard on the top is for further connectivity via addresses $5E and $5F, and Michael explained that he plans to attach a small breadboard to the top for further customization and experimentation.

As you may have noted, he has used 2 different TI calculators as a keypad, one with a 4x5 matrix, and the other with a 4x6 matrix.

I think it's great that this old equipment is still being put to work in this way. (Thanks, Michael, for sharing!)
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