Future Domain SCSI controller for AT bus

[Steve Dyer]

In article <522 at m3.mfci.UUCP> bronson at mfci.UUCP (Tan Bronson) writes:
>for our '286 machines. A local dealer has recommended the
>Future Domain SCSI controller and claims this works with
>Xenix/Unix and that someone has this setup using Microport.
>
>    Has anyone had any experience with this board ?
>    Does this imply a special version of Xenix ?
>    Is this board related in anyway to the Tandy SCSI board ?
>	(I though the Tandy board was micro channel only)
>    Is there a better Xenix/SCSI combination ?

Future Domain has drivers for XENIX 286 and 386 which were written
by Corollary of Irvine CA, the multi-processor XENIX folks.  The way
it works is a little weird.  Apparently the current (< 2.3) versions
of XENIX are said to "only support two drives (of any type)".  This
would mean that if you have a AT floppy/hard disk controller with
at least one of the disks in use, you don't have the option of adding
another controller of any type.  Now, no one can really tell me why
that is, since UNIX really doesn't care, and the best explanation I
can surmise is that the XENIX "divvy" partitioning software layer
makes such a bad assumption, so two drivers for two different
controllers which both use the "divvy" partitioning scheme can't coexist.

So, how do you get a Future Domain XENIX installed onto a system?
Future Domain provides a means by which you insert your installation
diskettes on your running XENIX system, and they build a new diskette
which has their SCSI driver installed as the hd00 device in place of
the AT hard disk controller.  Presumably, you back up your AT disks,
build a new installation disk, reinstall XENIX on the SCSI drive,
and then restore from backup.

I didn't want to do that (my cartridge tape was frotzed at the time)
and anyway, the SCSI disk was loaned to me.  So, I tried to be smart
and built a new kernel with the SCSI device as just another set of
major/minor devices, keeping the AT controller as the primary
device.  (I was saying to myself, there's NO WAY that UNIX cares about
how many disks there are.)  You don't wanna ask what happened when I
accessed the SCSI, but I'll tell you anyway.  My AT controller activity
light went on, I heard a strange sound and lost a block of inodes!
Now, I don't blame Future Domain for this, but consider yourself warned.
When they say you can't use both controllers, they mean it.  I do not
believe there is any IO address conflict.

Future Domain has a good reputation for its 830 card being a very hot
SCSI controller, and that's completely without using DMA.  I haven't
used the XENIX driver for the reason I mention above, but it's probably worth
investigating.
-- 
Steve Dyer
dyer at harvard.harvard.edu
dyer at spdcc.COM aka {harvard,husc6,linus,ima,bbn,m2c,mipseast}!spdcc!dyer