• Please review our updated Terms and Rules here

Need AT drive type for WD382R

A

Acorn

Experienced Member
Joined
Aug 29, 2007
Messages
68
Location
Atlanta, GA
I have a Compaq Portable II with a dead Miniscribe 8425 21.4MB MFM hard drive.

I replaced the drive with a Western Digital WD382R 20MB RLL hard drive.

The Compaq has a Western Digital WD1003IWH controller.

The old Miniscribe was a TYPE-2 drive.

Does anyone know what the WD382R "drive type" is?
I know from TH99 that it has 782 cylinders, 2 heads, 26 sectors/track, 512 bytes/sector and 65535 precomp. Is there a table somewhere that decodes the drive types?
 
Last edited:
The "drive table" is usually in the controller's ROM back in the "good old days". Most 16-bit controller (and a lot of 8-bit controllers) had their own onboard formatting routine in ROM also. You would just input the C/H/S, pre-comp and LZ info and away it went.

Some also had a table that you could pick a type from. I've worked with the Compaq II, but don't recall which it had.

It may even do it through a setup disk,

HOWEVER, since the WD1003IWH doesn't show up with a lot of info, but was hooked up to a 8425, it's probably NOT a RLL controller, so, you're not going to get the 26 sectors out of the HD, just 17, which will give you, roughly, 13.6 MBs of space on it.
 
I'm pretty sure the COmpaq II's required a setup disk for the CMOS config.
That's still the early days. My Portable III with the ISA expansion box used a setup disk.


Tony
 
I've got the Diagnostic/Setup disks.
Yes, the controller is MFM so I know I'll end up with considerably less space on the drive. I just want to get the computer functional. If I had a different drive I would try it but I don't. :(
 
Well, I've got a nice 8438 here that would be a 8425 on a MFM controller, but, these suckers seem to go for a small fortune on the net (somewhere between 100 and 300 US).

You'd have to be out of your mind!!!
 
Druid6900 said:
Well, I've got a nice 8438 here that would be a 8425 on a MFM controller, but, these suckers seem to go for a small fortune on the net (somewhere between 100 and 300 US).

You'd have to be out of your mind!!!
Click to expand...
Yes, I would be out of my mind to pay that!
 
Oh, hell, I would never price it near that on my website.

I have a Zenith ZF-158-42 and it has an 8425 in it and someplace was asking $700US just for the DRIVE.

Some of these places are crazy and they just make my prices look that much more attractive.

I wonder if they actually find people with that much more money than brains.

Granted, I try to restore computers to their original configurations, but, that would be ludicrous.
 
Table of drive types for IBM & Compaq

Table of drive types for IBM & Compaq

The good news is I found a table of "Drive Types" for IBM and Compaq!

The bad news is my WD382R doesn't fit any of these types.

I have attached the drive type tables so they can help others.
 

Attachments

  • hdcmos.txt
    6.2 KB · Views: 1
Old hard drive info

Old hard drive info

I also found the following technical info for various old hard drives. It's useful for matching up with the drive type tables I posted above or for low level formatting.
 

Attachments

  • hdinfo.zip
    13.3 KB · Views: 1
AT drive type tables

AT drive type tables

Here is the drive table

Table of drive types for AT and compatibles.

DRIVE CYL HEADS WRITE CTL LANDING SECTORS
TYPE PRECOMP BYTE ZONE PER TRACK
===========================================================================
01 306 4 128 0 305 17
02 615 4 300 0 615 17
03 615 6 300 0 615 17
04 940 8 512 0 940 17
05 940 6 512 0 940 17
06 615 4 NONE 0 615 17
07 462 8 256 0 511 17
08 733 5 NONE 0 733 17
09 900 15 NONE 8 901 17
10 820 3 NONE 0 820 17
11 855 5 NONE 0 855 17
12 855 7 NONE 0 855 17
13 306 8 128 0 319 17
14 733 7 NONE 0 733 17
15 - - R E S E R V E D - - - -
16 612 4 ALL CYLINDERS 0 663 17
17 977 5 300 0 977 17
18 977 7 NONE 0 977 17
19 1024 7 512 0 1023 17
20 733 5 300 0 732 17
21 733 7 300 0 732 17
22 733 5 300 0 732 17
23 306 4 ALL CYLINDERS 0 336 17


Personally I am slightly confused about the prospect of adding an RLL drive onto a MFM controller system.

Then I read this article which implies it might work RLL drive with an MFM controller.


Shameless plug follows:

On our Cromemco support website there are also some other IBMish general info. So these drive types are from this directory

Also I squirreled away a set of searchable .PDF tables for most MFM RLL drives. This is here Drive Specs

Regards Agata and Marcus
 
An RLL drive will work on an MFM controller as RLL simply has more sectors per track. MFM is typically 17 sectors per track, whereas RLL is typically mid-20s.

For example, Miniscribe produced a pair of drives - the 8438 (RLL) and the 8425 (MFM). Both had 615 cylinders, 4 heads and 512 bytes per sector. MFM had 17 sectors per track, RLL had 26. Drives were initially formatted using RLL, but if did not prove to be reliable enough were then badged as 8425's. Ones good enough for RLL were badged as 8438's.

I have both of these drives, but I am lacking a suitable MFM controller!

In theory you could put an MFM drive on an RLL controller, but don't expect it to be reliable ;)

You can also put an RLL drive on an MFM controller - you'll lose space, but you should get a very reliable drive.
 
Druid6900 said:
Well, if you can scare up an appropriate RLL controller, you can use Compaq type 46 with the WD382R and only lose a little of the capacity.
Click to expand...
That sort of what I'm doing right now but it's not a great solution with what I have to work with.

I have a couple of FileCard-20's which are 8-bit RLL controllers combined with the WD382R. For the time being I stuck one of those in the Portable II and it works fine. The issue is that I still have to use the Compaq controller for the floppy port. That only leaves me 2 slots for the video, memory and lan cards. That's why I wanted to extract the WD382R from the FileCard and use it to replace the Miniscribe.
 
Well, I'll be testing out my HD controllers within the next week and I have a good mix of MFMs and RLLs (most of which have the floppy controller built in). Maybe I can fix you up with a RLL that will take care of the "not-enough-slots" problem if you're more concerned about function than authenticity.

What size board can you take for that thing?
 
Thanks for the offer!

I may take you up on it but, I would like to search around a little first and see if I can find a suitable MFM drive.

The Compaq controller includes drive and floppy ports but also serial and parallel. If I switch controllers I lose all of that. They crammed a lot on that one card.
 
Got an IDE drive to work!

Got an IDE drive to work!

Well, I don't need an MFM drive to get my old Compaq Portable II running.
I installed an old Maxtor 7131A and it works great!

The Maxtor is a 131MB (unformatted) IDE drive with universal translation so it can appear to a controller as any combination of cylinders, heads and sectors/track within its formatted capacity. The closest thing to it on the Compaq drive type chart is a Type-26 which is 118.75MB formatted.

The key is that the disk controller on the Portable II is actually IDE. The reason an MFM works in the first place is because there is a WD1003-IWH mounted to the bottom of the factory Miniscribe disk that converts MFM to IDE. COOL! :happy5:
 
You must log in or register to reply here.
Back
Top