My apologies for cross-posting. I’m putting this on a few of the ‘80s forums.
I have a third party TRS-80 Model 1 expansion unit that I used with my System 80 when I first got disk drives. I’ve decided I should add some pics and info to the System 80 website as I know they were used here in New Zealand with System 80’s and, also in the U.K. for the Video Genie. A modified expansion cable was needed to convert from the System 80 expansion bus to the TRS-80 Model 1 bus on the unit but that was straightforward.
The interface is called a DP 1000 by General Northern Microcomputers Ltd. It has no RAM, but contains a disk controller and printer port. It was designed for ‘80s Model 1s and compatibles that had 48K of RAM under the keyboard, rather than requiring it in the expansion unit, as was the standard configuration. Many System 80s had their memory expanded under the keyboard so it was ideal for these. Mine was like this, and I found my DP 1000 worked very well with it.
Before I put some info up, I’m wondering if anyone knows any more about General Northern Microcomputers Ltd, the company that made the DP 1000? I’m pretty sure it’s a U.K. company. Also, most of the chips have their ID’s shaved off (see the circuit board image)?? Why would they do this? I can only assume it was to stop reverse engineering?
Here are some pics: