dyer@spdcc.COM (Steve Dyer) (05/30/87)
Well, I've been running SCO XENIX 286 for a few hours now on an IBM AT
with the Intel Inboard/386 card installed. I haven't pulled out any
benchmarks yet, but my impressions are, in this particular configuration,
it ain't particularly fast. In fact, it feels a bit slower than the machine
I was previously running on, a 8mhz, 0 wait state AT clone. I mention
this as a point of information for folks who might be surprised at the
lack of a clearly discernable difference. HOWEVER, you should take these
comments with a lot of salt because of the peculiarities of the installation;
with some few changes, your mileage (and mine) should differ. I plan to
mention any improvements as I discover 'em.
1. -- I'm using 16-bit memory only. I had real problems getting the POST to
get past 256K of memory when the AT motherboard was jumpered to have
only 256K of memory, with the Inboard's memory mapped into the 256-640K
area. There were other problems, such as the requirement that the
Inboard's memory start either at 256K, 1mb or 1.5mb, something which
didn't work well with my set of 16-bit memory boards. Rather than
hunting this down immediately, I elected to try the board without
its 32-bit memory.
2. -- The Inboard can run at either 8 or 16mhz with its cache off or on.
At power-up or reboot, it resets to an intermediate speed; I believe
it's 8mhz, cache on. Intel provides a couple of DOS programs which
toggle the speed between the four different possibilities. Unfortunately,
if you're running XENIX, you're presently stuck with this default
speed, and can't easily take advantage of the 16mhz/cache combo.
I plan to write a kernel driver which can perform the necessary
OUT instructions to accomplish this.
Clearly the verdict is out until I get the Inboard "up to speed" with its
own memory and running as fast as possible. The XENIX 386 toolkit is
on order, and I look forward to playing with a real 32-bit C compiler.
Some other random comments: I spoke to Intel tech support and the woman
who helped me was really superb. It was an unexpected pleasure to talk with
someone in such a position who understood exactly the kinds of problems
I was having and could answer them with real authority. Not my usual
experience with customer support.
I'm using this with an IBM EGA card. Unfortunately the POST screams bloody
murder with an infernal beeping whenever the Inboard is installed, and also
likes to think that its a "40-column color display". SCO XENIX fixes
this immediately, and under DOS, a "mode bw80" will do nicely. But be sure
you run SETUP for a new EGA installation without the Inboard installed,
because the diagnostics (1.02 is what I have) are determined to think
you're running a CGA on your TV.
The installation is best left for folks who really feel comfortable
ripping an AT apart. Be sure that you have the right "cable kit" for
your machine--depending on the 286 carrier, you need a JEDEC cable kit
(for most compatibles) or a pin array (for the AT.)
I'm still amazed that it works at all.
--
Steve Dyer
dyer@harvard.harvard.edu
dyer@spdcc.COM aka {ihnp4,harvard,linus,ima,bbn,halleys}!spdcc!dyer