Disabling SCSI parity checking to dump disk on ACB4000 MFM-SCSI adapter?
cctalk at gtaylor.tnetconsulting.net
Thu Sep 24 10:23:25 CDT 2020
On 9/24/20 1:12 AM, Camiel Vanderhoeven via cctalk wrote:
> I used an Ancot Ultra2080/Lite SCSI-bus Analyzer. This is a device
> that connects to a SCSI bus and has a serial port. Over the serial
> port, you can monitor the signals on the SCSI bus, and use it as a
> SCSI protocol analyzer. There’s also the possibility to construct
> and send a SCSI command. Rather than connect a serial terminal to the
> serial port, I connected a PC, then wrote a C program to control the
> Ancot. I had the Ancot send commands to the disk to read a sector at
> a time, and recorded the data sent in response to a file to create a
> disk image. Slow as hell (each byte on the disk requires sending two
> hex characters and a space over a slow serial line), but it works. I
> had to make several passes over the disk, because occasionally the data
> received from the disk turned out to be data from a different sector
> than the one I was trying to read. By reading the disk multiple times,
> I could get rid of these mis-read sectors.
Very NICE hack Camiel. I like it!
I am a little surprised by getting different data for the same sectors.
I find that mildly concerning. Did you do something like read each byte
multiple times to find a majority sample? 2/3, 3/5, 4/6, etc? Do you
think the different data was an artifact of the old drive? Or was it a
tickle of a bug elsewhere in the chain?
Grant. . . .
unix || die
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