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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