An RCA CDP1802 (COSMAC) trainer of unknown origin

(Update: I now know the origins of this machine. See the bottom of this article and the comments)


I try to be disciplined in my collecting. I have a list of desirable machines which I regard as classics and these are the only ones looked for. If other units find their way into my collection it's because they are donated. Never look a gift horse in the mouth, right?

However there are occasions when you come across something unusual. Something out of the ordinary that just screams "vintage". Something that you can pick up for a song. Such was the case with the single board microcomputer shown below. I picked up this weird contraption from a computer and books fact the same one I got the recent Apple IIes.

Remarkably the machine actually goes! Not only that, but after a good clean it looks quite presentable!

COSMAC Trainer

Figure 1. The machine in action

But what is it?

Good question. When I picked it up I figured it was some kind of trainer. However, I wasn't sure. The case is obviously home-made but the circuit board is well-labeled. The words "LANG 1984" and Commander appear there. Some of the pin labeling suggests it could possibly be used to program EPROMS?

I decided to ask those who were more knowledgeable than me. I placed ID requests both on the Vintage Computer Forums and the New Zealand Computer Vintage Forums. The discussion is here and here respectively.

Lang 1984 Commander board

Figure 2. A close up of the board

The consensus

There were a few suggestions. One was that it was a microcontroller that had been adapted for hobby use. However, the most likely summation was from Chuck(G). He feels it's a simple trainer for the CDP1802 microprocessor along the same lines as the COSMAC ELF and its derivatives. Chuck is a knowledgeable guy and his detailed explanation on the VCF mentioned above is plausible.


Just who made this board is still unknown. Chuck seems to feel it's a one-off. However, a 1997 document for an MCL precision positioning system briefly mentions a "LANG Commander console" by LANG GMBH & Co from Germany. The similar names may just be coincidental. Alternatively it's possible that this could be an early board by the same company which grew up into the LANG Commander console mentioned. If I find out, I'll update the blog to reflect the new information. If you are reading this and YOU know, get in touch!


It's a cool, retro-looking piece and I'm pleased to have it. I know an operator needs to load code into memory byte by byte using the keypads but I have no idea how to do this and there is no hope for a manual. Someday I might spend some time learning by trial and error.

11th December, 2011

Update: I now know what this is. A homegrown trainer designed by the late David Lang, electronics tutor at the Community College, Wanganui (as explained on this website). A piece of local history. See more in the comments.
7th June, 2012


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