I used to get this all the time when I had my RDB set to Synchronous
mode. I could never get that running reliably no matter what
length/termination was on the cable.
If I were you I'd select Asynchronous mode as the chips are telling
each other to switch down to maintain reliable transfer.
You might get funny things happening if you have Reselection enabled
too.
If you keep it to Asynchronous/No Reselection the SCSI chain will
determine for itself what is the best speed to talk at.
Maybe use Phase5's SCSI_Config_1.27
Also for SCSI 1 keep total cable length below 4m, 2m for SCSI-2 and
have an active terminator for SCSI-2.
