RetroChallenge 2017/10 – Bringing REX back to life!

It’s time, once again, for Retro Challenge. For those unfamiliar w/ RC, it’s a month-long personal challenge to do a project involving retro/vintage computers. It’s run twice a year, currently in April and October (although it used to have a different schedule). Entries are “judged” and there are “prizes”, but there are no winners and no losers — to borrow from the WOPR: The only losing move is not to play.

Previous entries on this blog documented by attempt at RC this time last year. Last year, my goal was basically to fix up a couple of my malfunctioning machines, and do some upgrades. I didn’t have much time last year to work on it, so I considered that RC abandoned-in-place, more or less. Eventually I got the machines running and all is right with the world.

This year, though, I have more concrete goal: Bring the REX back to life!

No, I’m not starting another Jurassic Park. The REX is the flexible option ROM replacement for the Tandy 100/102/200 portable computers. I plugs into the option ROM socket and allows you to load multiple option ROM images and switch them dynamically. It also does RAM backups to its flash memory. Basically, it’s like adding a 1MB SSD to your Tandy 100 and it’s awesome. More information can be found at

But, it’s not available from Club 100 anymore. Between the passing of Rick Hansen (RIP), and lack of available time by the members who took over Club 100, the REX has been out of production and out of stock for some time. Every so often, a person would ask about getting a REX on the Club 100 mailing list, but the answer was always that there were none to be had.

Then, back in Feb of this year, Stephen Adolph basically made DIY plans for REX available, along with board design, software and flashing instructions. Brian White took that material and ran with it, eventually producing a functioning REX unit. Brian then made a Bill of Materials available through DigiKey and posted very detailed instructions for DIY’ing a REX. This caught my eye, as I’d been wanting a REX for a while. But, the stars were not aligned, and the idea sat in my mailbox.

Until now…

Last week, I successfully built my first REX board. The construction involves very fine-pitch SMD soldering, as well as Xilinx programming and “in-system” programming in the Tandy itself. Another member on the list sent me supplies he had purchased earlier, intending to build one for himself, so I assembled it for him. There are several steps, but the overall process is not actually hard, and the REX worked on my first try! Needless to say, I was starting to get excited.

So, my RetroChallenge for 2017/10 will be to get REX out of “unobtanium” status and into the hands of anxious Tandy 100 users. Originally, I wasn’t going to do an RC this year, because I was going to work on the REX instead. For whatever reason, that didn’t seem like a “proper” RetroChallenge – it felt like more of a logistical process than a “retro” challenge. But, after more thought, I realized, it’s actually the perfect RetroChallenge. Doing a project like this will involve a lot of learning on my part, it’s information that will likely benefit the community, and there will be lots to document in this blog.

So, I’m in. Hopefully, in 28-ish days, the world may not have a new stock of REX boards yet, but REX will be well on its way back from “extinction”.