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Jorg
November 30th, 2003, 03:33 AM
My 5170 AT is working with a type 2 full height Winchester (20 megs)- can't see the exact type right now.

I found a Miniscribe 8425 20 MB HD that I want to add, but I can't get it to be recognized by the bios.
I have seen it working in another PC, so ist not broken. It also spins up normally. Its jumpered ok, according to the documentation that I found.
The PC is a model 99, so only 16 choices in BIOS. I tried all 20 mb and 30 mb ones to no avail.

I'm not sure about the controller card- it says (c) 1983 FIXED DISK-FLOPPY DISKETTE, and has a lot of WD chips on it.
Some sticker says REVX7-ECO1611, http://members.home.nl/charon.styx/5170HDctrl.jpg.

Would there be anything left to try?

mbbrutman
November 30th, 2003, 07:16 AM
I'd love to know what type of drive you have in there now. My 5170 has the Seagate ST-225 which is 20MB but half height. Is yours the CMI drive? If it is, be careful - they had a horrible reputation.

On the other hand, the Miniscribe 8425 is supposed to be a nice reliable little drive. It's definitely an AT Type 2, just like the Seagate and what you have now. So keep the CMOS settings at Type 2 while you are testing. My guess is that you have a cabling problem.

Don't worry about the controller - it looks like a 16 bit MFM controller to me. It looks like a genuine IBM controller too. If it works for one drive, it'll work for your Miniscribe.

Have you tried uncabling your existing drive and hooking the new drive to that cable? Just as a test, to make sure it isn't a master/slave issue ...


Mike

Jorg
November 30th, 2003, 07:29 AM
I was curious myself, so I took it out:
the drive that came with the system is a Seagate ST-4026.
(what does CMI mean?)

Does that make sense?

I tried the "replace option" (just detaching the original and connecting the miniscribe, but it didn't help.

I also tried (its raining today.. ;) ) to put the MFM controller in a 486 (with onboard IDE, that I switched off), but couldn't get it to work.

Super-Slasher
November 30th, 2003, 07:33 AM
Strangely enough, it seems the hard drive recognition in the PC AT's could be a little troublesome; I went through the same thing when I first got my PC AT's.

The only thing that worked for me was using a copy of Disk Manager to change the hard drive table in the BIOS (if nessicary), install the hard drive, and then format it/scan it to verify disk quality.

I have this program to download if you want, in a zip file. Just send me an e-mail and I'll send it off your way. It fits onto one 360KB 5.25" floppy and is -not- a bootable program. You have to use a DOS boot disk then use DM.

With DM I've installed various hard drives without problems into my PC AT's including a "huge" 85MB Miniscribe... DM had to partition the drive into two virtual drives because the PC AT BIOS couldn't handle drives larger than 75MB.

Jorg
November 30th, 2003, 07:46 AM
I have this program to download if you want, in a zip file. Just send me an e-mail and I'll send it off your way. It fits onto one 360KB 5.25" floppy and is -not- a bootable program. You have to use a DOS boot disk then use DM.


That would be great- I will send you an email on your hotmail adress.

Erik
November 30th, 2003, 12:37 PM
(what does CMI mean?)

IBM originally contracted with Computer Memories Inc. to make the 20 Meg HD for the original AT.

The company went from making a few hundred drives a month to several thousand a week to meet IBM's demand. While they got production up, quality suffered massively. One of the PC mags of the day actually said that if you have a CMI drive in your AT then it is guaranteed to fail and you should replace it immediately.

A competing drive maker advertised a swap program where they would replace the CMI 20 with their drive and offer a discount of something like $50 for the CMI drive. They got permission from Florida state to create an artificial reef out of the exchanged drives off of Boca Raton in sight of the IBM PC plant down there.

I don't think there are many CMI drives left today and if there are, they almost certainly don't work.

Erik

Jorg
November 30th, 2003, 01:28 PM
@ CMI: pfoei!

@Story
Very strange:
The Miniscribe is being recognised only when I:
1) put it on the 'D' connector and the second datacable
2) I enter 'type 2' in the bios for the first disk (disk 0) (this is weird!)
(so bios= 1st drive and cables are 2nd drive !?)

Any other way, the disk is not recognized.
There is a drive select jumper on the drive, this has to be in the 'first drive' position for the above. If I put it in 'second drive' it is in no cicumstance recognized.

Then Diskmanager recognizes it correctly as 21.4 mb type 2.

However:
If I do connect it as above
a) The drive led *stays on*
b) Diskmanager proposes low level format, but if I do, it gives massive errors (looks like wrong geometry)

:?

mbbrutman
November 30th, 2003, 06:02 PM
I have an AT with a CMI drive on it. I've not turned it on yet. Based on what happened with the CMI drives, it's better left as it is - if it does turn on, it may not work for long!

Something is screwy about the drive jumpers (if it has any) or the cabling. The procedure should be:

Set BIOS type for both drives to type 2, as they are both type 2 drives. That should set the correct geometry in the BIOS.

Connect the first narrow cable to your C drive, and the second to your D drive.

Connect the fat cable to both drives.

Something to look out for - the last drive on the chain needs termination. The drive in the middle should have no termination. What I mean by termination is a terminating resistor pack which comes on the drive. The terminator keeps signals from reflecting back down the cable when it hits the end of the cable. (The bits just don't fall off.) The drive in the middle has to have the terminator removed, and the drive at the end of the cable has to have the terminator installed.

It sounds like in your case the Seagate has a terminator because it was the only drive in the system. Otherwise, it wouldn't have worked. But it sounds like the Miniscribe does not have a terminator installed. If the Seagate is in the middle of the cable that's going to cause some nasty problems. If the Seagate is at the end and it still has the terminator, then the Miniscribe should be ok. (At least as far as termination goes.)

Floppies and SCSI drives work on the same principle - the are all related. Devices in the middle of a cable need to be unterminated. Devices at the end of the cable need termination.

Let us know how the drives are terminated .... I'm almost embarassed that I didn't think of that earlier.


Mike

mbbrutman
November 30th, 2003, 06:16 PM
I couldn't resist .. it was time to turn the AT on and see if the CMI drive was alive.

This was a machine I rescued from work a few weeks ago. I had found it in a junk bin, and it had been in storage for a while. When I opened it up to see what was inside it I nearly fell over when I saw the CMI drive in it.

Anyway, it takes a while for an AT to count memory. That was the longest 45 seconds I've spent in front of a machine in a while. It sounded like the drive was spinning though, and there were no grinding or squealing noises. Sure enough, it booted DOS 5. I should have video taped it. :-)

barryp
November 30th, 2003, 07:12 PM
Would there be anything left to try?

A thought or two or three:

MFM hard drives also have drive jumpers. Your C: drive should be set to the lower-numbered position and have its' 20-pin control (?) cable connected to the controller card's lower numbered connector.

Also, the 34-pin data cable should NOT be a floppy cable with a twist in it. There are hard drive cables with a twist but switching different wires.

AND, it's possible that the drive had been formatted RLL (25 or 26 sectors per track vs. the normal MFM 17 sectors.)

Jorg
December 1st, 2003, 11:49 AM
thanks- that's a lot of info- project will continue next weekend :P

Unfortunately i have only one 20 pin control cable, so I can only try one drive at the time. There are two control connectors allright.

The 34 pin cable has a twist, but I don't think it is a floppy cable, because the connectors are labelled "C" and "D".

AFAIK both the Seagate (that works) and the miniscribe are terminated.
See a picture of the Miniscribe of what I think is the terminator pack here:

http://members.home.nl/charon.styx/1.jpg

I just pulled it off a bit to make it more visible, it was completely on the pins
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mbbrutman
December 1st, 2003, 05:46 PM
I'm not sure that is the terminator pack. The terminator pack is supposed to be near the edge connectors. Every resistor pack that I've ever seen has also been a single row of pins, looking more like a multi-legged capacitator.

Check this web site - it's a great resource:

http://www.webtradecenter.de/pcdisk/



Mike

barryp
December 1st, 2003, 09:56 PM
See a picture of the Miniscribe of what I think is the terminator pack here:

No, that's positively not the terminator. I have a Miniscribe 8438, which I believe is an RLL version of the drive pictured.

What you have pulled back is the ribbon cable connecting to the drive itself.

Look on the opposite end near the 34-pin edge connector, you should see a thing that's labeled RP1 which is the termination. One of the jumpers to the left probably selects termination/no termination.

I'd be happy to send you a cable but it would cost far more for shipping than it's worth.

Jorg
December 1st, 2003, 10:36 PM
See a picture of the Miniscribe of what I think is the terminator pack here:

No, that's positively not the terminator. I have a Miniscribe 8438, which I believe is an RLL version of the drive pictured.

What you have pulled back is the ribbon cable connecting to the drive itself.

Look on the opposite end near the 34-pin edge connector, you should see a thing that's labeled RP1 which is the termination. One of the jumpers to the left probably selects termination/no termination.

I'd be happy to send you a cable but it would cost far more for shipping than it's worth.

I found the rp1: it has a red coloured sort of stripe on it. The jumper in line with it is JP22- that might be it. Gonna try next weekend- i'll be off a few days.

thanks a lot!

Jorg
December 6th, 2003, 02:57 AM
I got it to work! Thanks a lot all!

Now I'm looking for a 20 pin control cable ;P

mbbrutman
December 6th, 2003, 09:36 AM
So it was a termination issue?


Mike

Jorg
December 7th, 2003, 07:50 AM
The terminator was in place- the jumper that I thought was activating it made no difference however.

I got it to work as single, first harddisk, after I moved the drive select jumper on from position 'disk 1' to position 'disk 2'.

Now this was trial and error, and it seems totally unlogical to me.
It is on controller cable 1, data cable 'C' position, first HD in bios, but the drive number jumper on the drive is disk 2.
Strange, but it works!

Now I'm having a controller cable on the way, so I hope I still get it to work in a two drive situation, but at least I know the drive is ok.