From: dpalmer@mcnc.org (W. Dev Palmer)
Subject: Responses: XT drive/controller in AT
Organization: MCNC Center for Microelectronics, RTP, NC
Distribution: usa
Date: Thu, 13 Aug 1992 13:47:51 GMT

Thu Aug 13 09:31:22 EDT 1992

Fellow Netters:

I posted an article about using an XT hard drive and controller in an
AT last Monday, and got many helpful responses.  There were so many
responses that it seemed like it might be worth posting a summary to
the newsgroup.  Here goes ...

Thanks,

Dev Palmer
dpalmer@mcnc.org
MCNC Room 212
P.O. Box 12889
RTP, NC  27709-2889
(919) 248-1837
(919) 248-1455 FAX

> From @ricevm1.rice.edu:B645ZAV@UTARLG.UTA.EDU Mon Aug 10 10:47:07 1992
> Message-Id: <01GNEUCTHBBK002ET3@utarlg.uta.edu>

> Dear Dev,

> This exact situation happened to me just a week ago...  I posted almost the
> exact same question on usenet and received a ton of answers (as you probably
> will).

> I am running a 8-bit WD controller in a used 286/12 motherboard.  You have to
> tell your CMOS that no hardrive is installed.  The BIOS extention in the
> controller will then run the drive.  You will be able to boot from the HD.

> Also, you will probably need to reformat and change the interleave on the
> drive.  Mine was set to 4 and while it was in the XT I got transfer rates of
> around 150 Kbytes/sec.  When I installed it in the AT the transfer rate
> plummeted to 26 Kbytes/sec.  I changed the interleave to 6 and now have the
> rate up to 126 Kbyte/sec.  One of the message I received told me that 16 bit
> 1:1 RLL controllers were pretty cheap and I could achive rates of around 500
> Kbytes/sec!!  I am current looking looking for a used one in the local 
> computer stores.

> From irvin@ucunix.san.uc.EDU Mon Aug 10 12:17:33 1992
> Message-Id: <9208101610.AA20044@ucunix.san.uc.edu>

> Hello,

>	 I did the XT to AT upgrade last year.  In the setup, I chose "no
> drive".  What this does is after the setup settings take effect, then the
> system goes out to the bus and loads bios off of the cards.  The XT
> controllers have this bios on board (I used the Western Digital board).
> One thing that I noticed, was the the hard drive was slower than before. 
> After a few months, I got an old (cheap) AT floppy/hard drive controller,
> and was much happier.
 
> From faruque@sun.soe.clarkson.edu Mon Aug 10 13:53:34 1992
> Subject: Re: Using XT hard drive controller in AT?

> Hello,

> Yes, it is possible. I did it long time ago. You have to tell the
> SETUP that no drive present (as you mentioned). The XT controller has
> an on board BIOS that will take care of everything. Only thing you
> have to do a low level formatting using the DOS DEBUG command (look at
> the manual of the controller card).  If you do not know how to do the
> low level formatting, then let me know and I will explain more. After
> doing lowlevel formatting, you have to run FDISK and highlevel FORMAT
> to transfer the operating system to the hard drive (see DOS manual).
> That's all. You should now be able to boot the machine from the hard
> drive.

> Of course the performance will be slower with a 8-bit card. But it should
> give your friend a working machine until he wants to put a 16-bit card
> (a used one should be around $20 or even less). Hope that helps.

> From fordke@infonode.ingr.com Mon Aug 10 14:17:30 1992

> XT cards will work in AT motherboards.  Nothing special to do.
> Most ATs have both 8 & 16 bit slots.  You can plug XT cards into
> either.  The extra connectors on the 16 bit slots are unused in
> this configuration.

> From gdfwc3!kuwait!tod@texsun.Central.Sun.COM Mon Aug 10 20:17:49 1992

> Would you forward or post the responses to your question.  I would like to
> know also.

> From @scapa.cs.ualberta.ca:davem@ersys Wed Aug 12 01:32:38 1992
> Message-Id: <2qXcPB2w165w@ersys.edmonton.ab.ca>
   
>    Telling setup there is no hard drive should work, but if you can
> afford a new controller, I'd stongly recommend you get one or you lose
> a big advantage of switching to the AT motherboard -- faster disk I/O.

>   The system should boot from the hard drive.

>   One Caveat ... because of the faster system clock speed the interleave
> currently set on the hard drive (probably 3 or 4) will be too low.  The
> drive should be low-lever reformatted with an interleave of at least 5 
> (better too high than too low).  If you have access to a copy of Spinrite, 
> you can use that to determine the optimum interleave.

>   If you should uprade to a 16-bit controller, you'll also have to re-format,
> with an interleave or 1 or 2, depending on the controller.

>   Good luck.  If I can be of any further help, feel free to ask ..

> From balr!vpnet!cgordon@clout.chi.il.us Wed Aug 12 01:33:57 1992

> Tell the SETUP program that there are _no_ hard drives installed.  The
> XT controller has its own BIOS extension that will make the truth
> known to the rest of the machine.  You _will_ boot from the drive on
> the XT controller.  It's kinda like magic.

> From DAPARISH@BIIVAX.DP.BECKMAN.COM Wed Aug 12 17:39:17 1992

> How these 8 bit XT ctrlrs figure out the drive params (other than by jumpers)
> I don't know, then again when the XT's came out there were only 5/10/20 meg
> disks. but the idea is the ctrlr figures it out for itself (thats why
> the AT setup should be for NO DRIVE). It should still be able to boot from
> disk (via ctlr bios).  
> It's probably worth a try. If it doesn't work, AT (16bit) MFM controllers can
> be had for $25.

> From paranjpe@leland.Stanford.EDU Thu Aug 13 04:58:14 1992

> I just did this with an ST-250R Seagate 40Mb drive with an ST11R
> controller.  I told the CMOS setup there weren't any hard drives.
> This works since the XT card has its own BIOS which gets detected upon
> powerup, and installs the INT13h interrupts for the hard drive.  It works
> great!  I like the ST11R controller.  You can map it at any 32K boundary
> from C800-E000.

Thanks to all who responded.

Dev Palmer