[comp.sys.nsc.32k] problems encountered with SCSI

des%musashi.wpd.sgi.com@SGI.COM (Des Young) (02/26/91)

HI,
  I know this is not direct help ... but, just so you know things can work.
I have OMTI and Adaptec controllers working with floppies and winis on my
pc532. I am currently only using the DP8490, but obviously have more than
one controller.
  In fact, I have a revamped SCSI driver, it has a separate FLOPPY and WINI
task in the kernel, and I am just adding the SCSI printer support. The driver
allows more than one task to call it, by queuing requestors (I have done this
in the hope of a multi-threaded FS someday). I intend to allow a direct call
from user to SCSI task (bypassing fs) just for the purpose of backing up
(i.e. have both the WINI and FLOPPY tasks running).
  Although the driver is table-driven, and can be programmed to direct any
device to either the DP8490 or AIC6250, the AIC6250 support is not currently
working. In fact, I had a disk crash last November caused by trying to use
the AIC6250 and DP8490 together. Which brings me to ...
  Has anyone been using the two controllers together ? My crash was caused
when I switched between them, somehow the DP8490 got a bum command set,
causing it to scribble over the disk. I only started working on my driver
again 2 weeks ago, and had to completely build my system from start again.

  Oh yeh, for your problem... the Adaptec controllers like the following
command sequence:
	rezero, test_unit_ready, read_capacity
Of course, this is after you have formatted the drive already (when the
controller has the mode info hidden away on track 0).

If you are trying to use it before formatting, forget it. To format, use
	rezero, test_unit_ready, mode_select, format, read_capacity.

The Adaptec controllers are rather neat in the firmware, shlokky hardware.

Des.

eyal@echo.canberra.edu.au (Eyal Lebedinsky) (02/26/91)

Hello all,

This may be stupid, but I did it myself before: the SCSI uses CONN16 (the one
close to the expansion connectors) as we have no 6250 driver yet.

-- 
Regards
	Eyal