CS80 describe of /dev/rhd:
  controller:   0x8001  installed unit word
                  1250  max instantaneous xfr rate (Kbytes/sec)
                     0  CS/80 integrated single unit controller
  unit:              1  generic device type (flexible or removable media)
                079350  device number (6 bcd digits)
                   256  # of bytes per block
                    16  # of blocks buffered
                     0  recommended burst size
                   240  blocktime (microseconds)
                   930  continuous average transfer rate (Kbytes/sec)
                    80  optimal retry time (centiseconds)
                    84  access time parameter (centiseconds)
                    31  maximum interleave factor
                  0x00  fixed volume byte
                  0x01  removeable volume byte
  volume:         1320  maximum cylinder address
                    12  maximum head address
                    91  maximum sector address
               1579915  maximum single-vector address
                     1  current interleave factor