[Coco] A CoCo 3 Hard Drive System

[Didier Derny]

Yes, some early SCSI 1 devices are just  SASI devices renamed  SCSI
worked fine with early SCSI 1  controller but a disaster connecter to a 
SCSI 2

it's probably why a fuse was added to termpower

I was working on a connection between a commodore CBM 8000 and  Bull 
D520 drive
all document / drive were labelled  SASI and  renamed SCSI for comdex 1983


On 27/01/2015 10:29, Dave G4UGM wrote:
> 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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>>
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