[Coco] A CoCo 3 Hard Drive System

[Dave G4UGM]

I had forgotten that, but I seem to recall that you can get bitten with TERMPOWER on SCSI as well ....

> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Didier
> Derny
> Sent: 27 January 2015 09:01
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] A CoCo 3 Hard Drive System
> 
> beware with SASI / SCSI. the cables are slightly different
> 
> for example the SCSI 5v termpower is on pin often connected to SASI GND
> 
> the main symptom is a the 50 wire cable burning...
> 
> if you are lucky, the controller has a fuse and you have just blown the fuse
> 
> 
> I know that the guy working on SCSI2SD has improved his hardware to
> support old SCSI drives I'm not sure that it fully works works with SASI
> 
> 
> 
> 
> 
> 
> On 27/01/2015 09:47, Dave Wade wrote:
> > Its my understanding , from the Wikipedea page on SASI that it is broadly
> > equivalent to SCSI 1. So you would need something less than 1gb, probably
> > with the ability to disable parity. Many years ago I used one of these
> > adaptors on my Atari ST. Its also possible its ROM is hard coded with the
> > geometry of the Miniscribe drive. The Atari had a Geometry table in a file
> > you could update.
> >
> > Dave Wade
> > G4UGM
> >
> >
> >
> > On 27 Jan 2015 06:20, "Mark J. Blair" <nf6x at nf6x.net> wrote:
> >> 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:// <http://www.nf6x.net/>www.nf6x.net/ <http://www.nf6x.net/>
> >>
> >>
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