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Micom 2000
April 6th, 2005, 07:17 PM
I have a couple of Commodore PCs. A PC 10 and a PC20. One of them was accessing the HD until recently, when it died while I watched. No problem I thought since I have a stash of MFM HDs including about 6
Miniscribes which the beasts use. As I switched HDs none of them worked.
I cant believe all of them failed. (I haven't tested them on another older computer, achhh). Does anyone know if the C-PCs had something like the AT BIOS which required HD specs ?

Lawrernce

Thrashbarg
April 7th, 2005, 02:53 PM
I vaguely remember a friend saying years ago he had a Commodore PC and the BIOS was fixed for one type of hard drive, if this helps.

Terry Yager
April 7th, 2005, 04:39 PM
The only C= PC I'm familliar with is the ol' original Colt, which used an XT-IDE drive, with the controller built into the mainboard.

--T

patscc
April 14th, 2005, 07:02 AM
A few questions.

1. What's the part number of the original "failed" drive, I'd like to look at the jumper settings for it. While you're at it, what part numbers are the ones you're using as a replacement ?

2. On your subsequent drives, narrow down "none of them worked"
Did they not spin up, does the speed keep fluctiating, what ?

4. If you boot with a DOS disk, does FDISK see it ?

As Terry mentioned, the PC10-III used an XT-IDE drive, which is the old style 8-bit IDE interface. If the Miniscribes are XT-style IDE, they should have XT after the part number( e.g. 8438XT )

5. Did the hard drive that failed connect to the 40-pin header on the board, or to a seperate card with two flat ribbon cables( in which case it's not IDE) ?

If FDISK doesn't see it, you might be able to load the low-level formatter routine for it, some of the very early XT-IDE stuff still had this hangover from the MFM days.
You can load( or try to load ) the formatter thus:
Run debug.com
At the >prompt, type "g c800: 5" and hit enter. If there's a low-level formatter, it should bring up a menu.

patscc

Micom 2000
April 17th, 2005, 03:10 AM
I have 2 PC III's. One a PC10 and the other a PC20. The PC 20 had a
Western Digital WD95028 IDE connected to the on-board socket. On closer examination I see one of the pins is broken off. I'll have to check my stash again. From what I read on usenet the socket required an 8-bit IDE.

The PC10 also has an IDE socket but was using an MFM Western Digital
controller card(m.3489 or on a stick-on label WD1004-27x) It has jumpers
w17 thru w22 and w25 thru w28 with w26 jumpered. It has 2 control connecters(DR0 and DR1) the narrow cable connected to DR0 and a single Data cable (guess you could use a double pair of connectors.)
That had a Miniscribe 8438. I have 2 additional 8438s and 2 8425s (Hope I didn't mix them up when testing them.) All seem to be jumpered the same. The Miniscribe 8438 was the working drive which failed. None of the drives I tested was recognized. I don't believe they booted up but will have to check again and see what F-Disk gives. I believe I checked them with an old copy of Disk Manager and also SpinRite but they weren't recognized. I'll try them on one of my xt clones to make sure.

Lawrence


A few questions.

1. What's the part number of the original "failed" drive, I'd like to look at the jumper settings for it. While you're at it, what part numbers are the ones you're using as a replacement ?

2. On your subsequent drives, narrow down "none of them worked"
Did they not spin up, does the speed keep fluctiating, what ?

4. If you boot with a DOS disk, does FDISK see it ?

As Terry mentioned, the PC10-III used an XT-IDE drive, which is the old style 8-bit IDE interface. If the Miniscribes are XT-style IDE, they should have XT after the part number( e.g. 8438XT )

5. Did the hard drive that failed connect to the 40-pin header on the board, or to a seperate card with two flat ribbon cables( in which case it's not IDE) ?

If FDISK doesn't see it, you might be able to load the low-level formatter routine for it, some of the very early XT-IDE stuff still had this hangover from the MFM days.
You can load( or try to load ) the formatter thus:
Run debug.com
At the >prompt, type "g c800: 5" and hit enter. If there's a low-level formatter, it should bring up a menu.

patscc

Jorg
April 17th, 2005, 08:20 AM
I did own a PC-10III, it was my first PC.

It has an 8 bit IDE controller, not MFM!

patscc
April 17th, 2005, 08:36 AM
Which pin? Sometimes one of the center pins, I think it's pin 20, was dropped , and the hole in the socket that matched was filled in to help in keying the cable so you didn't insert it the wrong way.

Amazingly enough, you can still find the manual for the WD1004-27x on www.westerndigital.com, search for "WD1004-27"
Which everybody kept their old docs online.


On the miniscribes, the term pack sits right above the controller cable's connection( the wide cable ), and it looks to be a sip.

Right next to it is a drive select jumper block, pin 1 should be on the left side of the block the lower pin( pin closest to the edge of the PCB)

DS settings are:

Jumper 1 2 3 4
Drive 1 closed open open open
Drive 2 open closed open open
Drive 3 open open closed open
Drive 4 open open open closed

Jumper 5 is not used

For the WD drive, pin 1 is the lower pin and sits on the right side of the jumper block nexxt to the power connector.

Translation mode enabled
J8/jumper 1
open
Phyeical mode enabled
J8/jumper 1
cloeed
DMA demand mode dieabled
J8/jumper 2
open
DMA demand mode enabled
J8/jumper 2
cloeed

Interrupt Pequeet I IRQ 5
J8/jumper 3
open

Interrupt Requeet I IRQ 2
J8/jumper 3
cloeed

MISCELLANEOUS IECHNICAL HOlES
DMA Demand mode enabled:
Thie eetting allows a 2:1 interleave oppoeed to the etandard 3:1 in tranelate mode and the ueual 5:1 in physical mode. However, tbie opton can only be ueed in a eystem when the BIOS or operatng eystem can program the DMA controller in
the demand mode and sense the mode selection !!handshake!! function. (The DMA controller must also support the
demand mode.)
USER CONFIGURABLE SETI1NGS

stock setting is all jumpers open, but I don't know if that means it works in a commodore that way.

Hope this helps.
patscc

P.S. No, I don't remember all this stuff, I'm just lucky enough to have recently acquired a copy of the cd-based Micro House Technical Library, which contains pinouts and specs for all kind of goodies.

Terry Yager
April 17th, 2005, 08:38 AM
The MFM drive & controller may have been an add-in by a previous owner, who may have been unable to locate a suitable IDE replacement. XT-IDE drives never were very common, even back in the day.

--T

Micom 2000
April 17th, 2005, 08:34 PM
Yeah I also suspect the Card is an add-on to get more than a 10M
HDD. I have that same Micro House CD. It was in one of the editions
of Mueller's U&R PCs. I see that the Card is an RLL. Might be one source of my problems. I had forgotten about that CD. Too damn much stuff.

Lawrence