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

[Josh Dersch]

On Wed, Sep 23, 2020 at 1:28 PM Michael Engel via cctech <
cctech at classiccmp.org> wrote:

>
>
> On 9/23/20 8:54 PM, Grant Taylor via cctech wrote:
> > On 9/23/20 12:51 PM, Michael Engel via cctech wrote:
> >> Do you know if is there another OS which would make it easier to
> >> change crucial SCSI parameters in the driver (config) or maybe a
> >> specialized tool that could help me to image the disk?
> >
> > Try booting off of a Linux live CD / DVD and seeing if it will behave
> > any different
> Not really, unfortunately. The error messages are a bit cryptic:
>
> [ 1069.277571] (scsi8:A:0:0): Sending SDTR period 45, offset 0
> [ 1069.278961] scsi 8:0:0:0: Attempting to queue a TARGET RESET message
> [ 1069.278964] CDB: 0x12 0x0 0x0 0x0 0x24 0x0
> [ 1069.278975] scsi 8:0:0:0: Command not found
> [ 1069.278979] aic7xxx_dev_reset returns 0x2002
> [ 1069.279286] (scsi8:A:0:0): Sending SDTR period 45, offset 0
> [ 1069.280736] scsi8: Slave Alloc 1
> [ 1069.543400] scsi target8:0:1: asynchronous
> [ 1069.543416] scsi8: target 1 using asynchronous transfers
> [ 1069.543420] scsi8: Selection Timeout on A:1. 0 SCBs aborted
>
> It seems that the problem lies in the firmware of the ACB4000, which
> doesn´t seem to support some standard commands, e.g. the INQUIRY
> command. Most recent Linux SCSI drivers seem to use this command.
>

Earlier versions of SunOS and Solaris know how to deal with Adaptec SCSI
bridges properly; I've done so on SunOS 4.1.4, for example.

I'd still suggest using something like this:
https://www.pdp8.net/mfm/mfm.shtml to image the MFM disks themselves.  A
friend of mine is in the middle of assembling a run of them...

- Josh