[Coco] A CoCo 3 Hard Drive System

[Mark J. Blair]

I just received an old hard drive system for the CoCo 3 from an eBay purchase. I bought it purely out of curiosity, since I've never used a hard drive with a CoCo before. I don't really have any expectation that it'll actually work, but it should be fun to experiment with. I figured that I might as well write a bit about it here in case it stimulates any interesting discussion. I don't know how long it'll be before I try using it, since I have so danged many projects, but one of these days it ought to make for a nice blog post.

The system consists of:

* An external drive enclosure containing a Miniscribe 3425 20 meg 5.25" MFM drive, a Xebec S1410 SASI to MFM controller card, and a power supply.

* A hard drive interface cart. Exterior is white painted metal, with no markings. The circuitry inside is very simple, and there's no ROM. It connects to the drive cabinet with a 50 wire ribbon cable.

* A floppy controller marked "Hard Drive Specialist Color Computer Controller". Inside there's a 28 pin EPROM marked "OWLWARE HDBASIC3".

* Some floppies and documentation.

I'll be pretty surprised if that Miniscribe drive works at all. Notes that came with the system suggest that the original owner was having trouble with it. My very first hard drive was a Miniscribe 20 meg 3.5" SCSI drive, part of a Supra 4x4 hard drive system for my Amiga 1000. That drive failed in a year or two as I recall. It was such a junky drive that it used a stepper motor for head positioning, but they didn't bother with an optical sensor for track 0; instead, the drive just hammered the head carriage against the stop at power-on to find track zero. Between that experience and the old tale of Miniscribe literally shipping bricks, I have no love for Miniscribe drives.

I'm not very familiar with SASI. It's my understanding that SCSI is a descendant from it. I wonder if some sort of modern SCSI drive emulator like the SCSI2SD card might work with that SASI cartridge?

Some of the wires inside the drive enclosure look like they've been nibbled a bit, and something that looked like a hamster food pellet was rattling around in the case. So, I'll want to examine it a bit more and patch some stuff up before I apply power for a smoke test.

-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/