[comp.periphs.scsi] 1542B SCSI TIMEOUT problem

jackv@turnkey.tcc.com (Jack F. Vogel) (02/06/91)

I am having a problem that I hope someone else out there has seen and solved.
I have a 25Mhz Atronics 386 system, I just purchased an Adaptec 1542B and
Maxtor 200Meg drive. When the system boots the Adaptec bios correctly finds
LUN 0 Target 0 and says its installed as C:, however running the onboard
diagnostics all commands are getting a TIMEOUT failure, it doesn't get
drive information, won't verify or format. Initially I thought there was
a problem with the drive and had it replaced, no go, the new drive had the
same problem. Then I put the adaptor and drive into a 10Mhz 286 system and
it worked fine! So there must be something relating to the speed of the
386 system that is causing the failure. In case it matters the bus is already
throttled to 8Mhz. Is there any magic with jumpers or otherwise that I can
do to get around the problem??

Any help or suggestions appreciated!!

-- 
Jack F. Vogel			jackv@locus.com
AIX370 Technical Support	       - or -
Locus Computing Corp.		jackv@turnkey.TCC.COM

alun@sunatb.UUCP (Alun Saunders) (02/12/91)

jackv@turnkey.tcc.com (Jack F. Vogel) writes:

>I am having a problem that I hope someone else out there has seen and solved.
>I have a 25Mhz Atronics 386 system, I just purchased an Adaptec 1542B and
>Maxtor 200Meg drive. When the system boots the Adaptec bios correctly finds
>LUN 0 Target 0 and says its installed as C:, however running the onboard
>diagnostics all commands are getting a TIMEOUT failure, it doesn't get
>drive information, won't verify or format. Initially I thought there was
>a problem with the drive and had it replaced, no go, the new drive had the
>same problem. Then I put the adaptor and drive into a 10Mhz 286 system and
>it worked fine! So there must be something relating to the speed of the
>386 system that is causing the failure. In case it matters the bus is already
>throttled to 8Mhz. Is there any magic with jumpers or otherwise that I can
>do to get around the problem??

I don't know about the Adaptec controller, but I know people who have
had problems with all sorts of cards that have add-in ROMS in
combination with 386 machines and shadow ROM. Disabling the shadow ROM
and thus forcing the code in the ROM to actually execute in the ROM over
the bus seems to do the trick. You'll probably also find that you will
have to keep the bus at 8 MHz. I have a cheapo Taiwanese adapter
(Longshine LCS286N) which refuses to run on an AT clone with a 10
MHz bus.

Hope this helps,
Alun Saunders