Repairing an Epson HX-20 – Introduction

I’ve recently got hold of a very interesting retro-tech bundle. I browse the auctions (both traditional and on ebay) from time to time and picked up this bundle. It ticks all the boxes for me – interesting item, with lots of original accessories and manuals, and a bit of a project into the bargain:

If you haven’t recognised it by now, this is an Epson HX-20 which is generally regarded as “the world’s first laptop” and which dates back to around 1980. It is quite a famous machine (although not particularly rare) and there’s a lot of information out there about it. However what’s interesting is that although it clearly was groundbreaking, a few shortcomings (notably the small screen) and the fact that it was probably slightly ahead of its time meant that outside some specialist applications (more later) it didn’t really ultimately succeed as a general purpose computer. The TRS-100 / Tandy 102 ended up as the clear winner in this regard.

I’ve got a lot of time for the Tandy machines and I did actually have one for a period many years ago. However what I really liked about the HX-20 was the clear quality of the design and build and also the fact that it has all the key aspects of a 1980s computer – screen, keyboard, storage and printer – in one very small and integrated package. There are also some very neat touches, such as the micro-cassette drive which is controlled entirely by the CPU.

The one I have came complete with the original carrying case, manuals, two boxes of printer rolls and various other documentation. It also came with a data logger also in its case with all the original documents, even the original invoice. I’ve got some more work to do to research it’s origin but it looks like it was used for something to do with testing and monitoring industrial heating systems. I’ll cover this aspect in another post. I’ll also continue the story in a separate post to keep things manageable. So without further ado…