Disabling SCSI parity checking to dump disk on ACB4000 MFM-SCSI adapter?

[Glen Slick]

On Wed, Sep 23, 2020 at 11:51 AM Michael Engel via cctech
<cctech at classiccmp.org> wrote:
>
> Hi,
>
> still working on backing up the Tektronix 440x disks. My current problem
> is that the ACB4000 SCSI-to-MFM adapter doesn´t support SCSI parity.
>
> I finally managed to find a PCI SCSI controller (Adaptec 2940) and a
> Pentium 4 PC with PCI slots and installed OpenBSD 6.7. I disabled parity
> checking in the Adaptec BIOS config and it detects a disk at ID 0 with
> no name. So far, so good.
>

If the Adaptec 2940 BIOS seems to detect the disk I wonder what would
happen if DOS was set up on the system and ASPI8DOS.SYS was loaded.
Would the Adaptec 2940 and ASPI driver respect the BIOS parity setting
and interact with the ACB4000 bridge well enough for a fairly simple
DOS program to be able to use the ASPI interface to send READ CDBs to
read the sectors from the device? If I had such a device myself to
experiment with I'd probably give that a try to see if it works.