AT&T UNIX System V/386

[Derek E. Terveer]

In article <2336 at tmiuv0.uucp> rick at tmiuv0.uucp writes:
> You should use the "user defined" drive type (under AMI BIOS, it's number
> 47, I believe).  Run your AT setup program and select the "user defined"
> drive type.  Give it the full geometry of the drive (1024 cylinders,
> etc.).  Unix should have no problems after that.

Unfortunately (for me, at any rate), I have an AMI BIOS + WD1006V-SR2 config-
uration that doesn't seem to like to talk to each other very well.  If I use
the BIOS "user defined" type of 47 and set my disk drive (a miniscribe 6085: MFM
1024 tracks, 8 heads, 17spt) parameters to 1024cyl, 8hds, 26spt, and then run
dos and debug to get into the wd menu, type 47 appears as 0,0,0 and the low
level format croaks, i.e., the machine hangs (no ctl-alt-del).  In fact, you
normally can't even access type 47 from the wd menu -- you must go to type 0,
and then back up one type to get to 47.  Otherwise, when scrolling forward
through the selections it jumps from type 46 to 0.  Very strange.

Now, if I use the wd "user defined" type of 1 and set my disk drive parameters,
when I get back into the wd menu (which I "must" do because it wants to reboot
right after setting the parameters), the drive parameters are set to the AMI
BIOS's idea of drive type 1, i.e., some disk with 305 cylinders, etc.
Apparently, the wd board can not overwrite the parameters in the CMOS RAM used
by the AMI BIOS.  Very inconvenient.  

So, the wd bios can't write into the AMI BIOS to save its user defined
parameters and the AMI BIOS user defined parameters don't appear to be noticed
by the wd board.  (Which came first?  the cpu bios or the controller bios?
(:-))

I quoted the "must" in the parenthetical sentence, two paragraphs above, because
I discovered that if I control-c the menu program just after "writing" the
parameters into the BIOS and just before I type return to initiate the reboot
and then rerun the wd menu program (g=cc00:5) the parameters that I entered for
the "user defined" type are still there (even though they weren't written into
the bios) and I can format the drive successfully (at 26spt and not 31 -- it
doesn't seem to want to accept 31 for some reason) with the specified
parameters.

Fortunately, unix doesn't really use the bios disk parameters for anything
other than booting, so as long as the bios thinks that there is a disk of some
sort out there that is bootable from the first few sectors on track 0,
everything should be ok.

Anyway, I also talked (afterward) to wd tech support and they stated that if
you use a disk type of 0, i.e., "undefined or no drive present" then, when you
select the low level format option, it will prompt you on the fly for the disk
parameters -- so that is another way of getting around the problem (if it works,
that is).  I haven't had a chance to try this since I have already gone
through the entire format/surface_scan cycle several times already and I am
just plumb tired of formatting and installing unix!  I will try this next time.

derek
-- 
Derek Terveer		det at hawkmoon.MN.ORG