🚀 go-pugleaf

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I had a similar problem, trying to match a CDC 36 MB drive to my AT.  My 
solution was to get "DUB-14" from Golden Bow Systems, San Diego, CA.
(See their ads in the back pages of PC Week and other rags.)  For all o
f
$95, I got two prom chips which plugged into the empty sockets on my
 motherboard and software that expanded the AT's drive type table from
 15 to over 50 drive types, with additional types being added.  It is very
likely that your drive will be supported.

Along with the software were installation notes for various removable hard
disks, and a special series of notes on patching Xenix 1.0 (S III) for
various non-standard drives.
 

A caveat.  

If you re-run IBM's SETUP program, you lose your hard disk until 
you rerun Golden Bow's setup program.

Also, you better be a bit adept with hardware installation.  Their 
instructions aren't for the faint-hearted.  However, their support was 
*excellent and friendly*.

No connection except as a satisfied customer, etc., etc., .etc.

Phil Burton
Xerox Corp.

The problem here is that the drive parameters are in ROM on the
disk controller board, and you're limited to the specific drives
that were anticipated by the controller manufacturer.  The Golden
Bow roms add additional drive parameter tables and possibly (I
have no way to verify this) the code to let the disk controller
read the drive parameters from the first sector of the disk
(thus the need to use the special Golden Bow device driver).
Some disk controller firmware, such as the Adaptec 2070, has
this feature built-in.

In article <260@psueea.UUCP>, waldref@psueea.UUCP (Greg Waldref) writes:

> I am trying to install a Seagate st-251 40 meg drive in my AT

We have found the simplest method of installing Brand-X disks in PC's
is to use a ROM burner to copy the BIOS ROMS (from the controller for XT,
from the motherboard for AT) to your PC, patch the drive table and burn
new EPROMS.  

	I attempted the software solution initially, but finally
gave up as I lost count of how many places the ROM was accessed directly
instead of using the vector.  (How do you get the vector there before
DOS boots?  That's a good question: you have to modify the boot sector
to put it there for you.  Unfortunately, the rest of the boot sequence
has to be tweaked as well since that vector is not used consistently
until you are up and running.  I was able to make it work by booting off
a diskette and having a small memory resident program supply the hard
disk table.  This is hardly worth it.)  Modifying the ROM also works
for SCO Xenix (but not Microsoft, ie. IBM, Xenix.  You have to patch
several different programs: /boot, /xenix, /etc/fdisk, /etc/badtrack and
maybe some others.  How do you patch these before you install Xenix on
your new disk?  Ahhh, good question!  You pretend you are a smaller
supported disk; install; make the patch; reinstall.)

* * * G R I P E * * *

	Both ROM and boot programs are the absolutely wrong place to
put disk size information.  Any intelligent DOS (or Unix port) would
put disk size info on the home block of the disk (the boot sector) 
where it can always be read.  I can only think of snivelling marketing
reasons why Microsoft did things the way they did.  (You should have
bought True Blue.)  Actually, the info is already there provided you
don't have to worry about reduced write current and stuff!  The number
of tracks/cylinder and sectors/track can be deduced from the partition
table since partitions are required to reside on cylinder boundaries.
-- 
Stuart D. Gathman	<..!seismo!{vrdxhq|dgis}!BMS-AT!stuart>

<++++++++++++++>

Rather than hassle with a PROM burner, which isn't something everyone has
lying around, just spend 95 bucks for "DUB-14", from Golden Bow Systems in
San Diego.  

You get a software disk plus two PROM chips to plug into your motherboard,
in the unused PROM sockets.  The software in the chips expands the AT's
ROMBIOS table of drives, by almost 50 extra.  

The approach is so good that it fools even the Dealer Diagnostics for the
AT.  The only problem you will have is that if you rerun the SETUP program,
you must rerun the Golden Bow setup program.

Just a satisfied customer, etc.  The usual disclaimers .....

Phil Burton
Xerox Corp.