PrintStar's Blog
Ramblings of a Fortran Nut
December 7, 2008 by Jeff

Retrochallenge Winter Warmup

I’ve been pretty silent on here since the release of rfk for the Rainbow 100, but I’ve had good reasons. Primarily I’ve been working towards another release of Draco, which has been a time-consuming process. Draco becomes more complex every day, and so many aspects need testing prior to release. However, I’m confident the Release 1.2 will be the best version yet.

On the Rainbow 100 and retrocomputing front, things haven’t been so peachy. I did acquire a boatload of Atari 8-bit software recently. I’ve had some fun going through that on an Atari 800XL. Desk space is limited, though, and to free some up, I began reassembling my Rainbow 100 on its E.T. stand. I souped up the Rainbow with my ultra-rare Turbow-286. The problems started, however, when trying to find a hard disk.

I may have mentioned before that Rainbow’s only use ST-506 interfaced MFM hard disks. These drives predate IDE drives. IDE drives, in fact, are basicly a ST-506-compatible drive with the controller on board the drive. The ST-506 is an amazingly dumb and mostly analog interface. I thought I had a substantial store of blank drives ready to go (mostly 20MB models), but I was shocked when I started to pull them out. It turned out I had maybe three blank drives over 10MB, and only one seemed to work.
The drive that did seem to work was installed in my Rainbow, and I formatted it using the ever-useful WUTIL package. I installed MS-DOS 3.10b on one partition and everything seemed fine.

As I began loading the drive with software, I hit a point where writing didn’t seem to work. No matter what action I took, copying, deleting, making directories, or creating fresh files, nothing would write beyond that point. In an attempt to fix the situation, I pulled and replaced the winchester controller (a.k.a. HD controller), repartioned, and reformatted. Eventually, the same phenomenon occurred.

I think I now know my Retrochallenge winter warm-up project. The Rainbow needs some other storage medium as these ST-506 interface drives slowly fade away into doorstops. I plan to create a Rainbow winchester controller emulator using the Parallax Propeller chip. The project goal would be to have a drop-in replacement board that would use the Propeller microcontroller to make the Rainbow think a winchester controller is present. The Propeller could store all files onto some sort of flash media, although it will probably interface directly to a PC at first. The plan is a bit ambitious because I have little to know logic experience, but the Propeller simplifies it by turning it into a mostly software project.

More to come on this one…

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