lane@cs.dal.ca (John Wright/Dr. Pat Lane) (02/13/89)
Hi: Once again, I find myself in over my head and calling out for help to
the net. I have an old IBM PC-2 (IBM 5150), one of the old 4.77MHz clunkers
with a 63.5 Watt power supply. It has a hard disk controller, a long card
labelled only IBM 1501492 with connectors for the wide control cable and two
data cables (for two hard disks) and no jumpers anywhere. There is a 10Meg
full height Miniscribe model 2012 hard disk (4 sides, 306 cylindars, I think).
Real antique stuff.
The drive was making *alot* of noise and fiddling with the static draw-off
strap effected only a temporary respite, so I resolved to replace the thing
with another old full height drive I had. This was a 20Meg CMI model 6426S
(4 heads, 613 cyls). To make a long story short, It didn't work. Set up
the way I thought would be drive 1, the machine booted with a floppy disk
OK (MSDOS 3.20) but on running FDISK, I got "Current Fixed Disk 1"..."Error
reading fixed disk". I tried every combination of drive select jumper posn,
twisted/non-twisted control cable, and 1st or 2nd data cable and got either
this message or a 1701 from the POST (in which case FDISK would say, "No
fixed disks present"). There appears to be a resistor termination pack
in place. (The Miniscribe didn't have jumpers but rather a block of traces.
It looked like it was set for drive select 1.)
I tried a 10Meg half height Seagate ST212 which apparently has the same no.
heads and cyls as the Miniscribe but I got the same results. An ST225,
same results.
I tried putting the drives in another machine (XT clone) with a WD1002S-WX2
controller. The two Segates worked fine, except that when I wired them as
drive 2 (either moving the drive select jumper or using the connector with
a twist in the control cable, and using the 2nd data cable), I got 1701 on
POST. This suggests to me that you can't have a hard drive 2 without there
being a drive 1.
However, both the Miniscribe and the CMI, connected to the WD controller
gave me the "Error reading fixed disk" problem. A slight annomoly here,
When the CMI drive was connected to the WD controller with the twisted
cable, the POST would hang and the drive made cycling noises like it was
continually resetting.
So I have a Miniscribe 2012 that works with the IBM controller but not with
a WD controller, a couple of Seagates that work with the WD controller but
not with the IBM controller, and a CMI drive that works with neither.
What's goin' on!!!
Is there something about these old drive & controllers that I don't know
that's doing this?
Does anyone have any knowledge about these items that would be relevant?
(I have docs for the WD controller and Seagate ST225 but I haven't yet
tried tracking down and contacting the manufacturers for the rest).
Was the comment I made about there having to be a drive 1 before a drive 2
is connected correct?
How does a system like this figure out the parameters for a particular
drive (ie. no. heads and cylindars)? I know about the default drive params
supposedly in ROM on the controller (pointed to by two DOS interupt vectors).
As I understand it, drive 1 is hardwired to be 20Meg, 4 head, 613 cyls and
drive 0, 10Meg, 4 heads and 306 cyls. I know this can be altered by
jumpers (as on the WD1002) or other means (I think you can write in your
own values on later WD controllers and OMTI controllers). Yet I could
use a 10 or 20 Meg drive with the WD controller without resetting anything.
The IBM controller didn't have any jumpers but it had a 10Meg drive as
drive 1. (Always wondered about this).
Should I be worried about trying to run a 640K system (it has an AST
SixPak Plus card) with a hard disk on a 63.5 Watt power supply? The
Miniscribe is marked (12V 1.5A, 5V 1.0A). The other drives aren't
marked with their power requirments.
Sorry to post another long rambling tiraid on my troubles but I'd
really appreciate some hints on this one...Thanks.
--
John Wright ////////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
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