Diskette Parameter Table

 A series of these 11-byte structures can be found at the vector address of
 INT 1eH (the 4-byte address found at 0:0078).  The list is also known as
 the "Disk Base Table."

 It specifies a variety of critical variables for diskette drives only.
 The table is set to default values by the ROM-BIOS and may be modified by
 DOS to improve diskette performance or increase battery life on a laptop.

DisketteParmRec
  Offset Size Contents
    
   +0      1  rSrtHdUnld   bits 0-3: SRT step rate time
                           bits 4-7: head unload time
   +1      1  rDmaHdLd     bit    0: 1=use DMA
                           bits 2-7: head load time
   +2      1  bMotorOff    55-ms increments before turning disk motor off
   +3      1  bSectSize    sector size (0=128, 1=256, 2=512, 3=1024)
   +4      1  bLastTrack   EOT (last sector on a track)
   +5      1  bGapLen      gap length for read/write operations
   +6      1  bDTL         DTL (Data Transfer Length) max transfer when
                           length not set
   +7      1  bGapFmt      gap length for format operation
   +8      1  bFillChar    fill character for format (normally 0f6H '')
   +9      1  bHdSettle    head-settle time (in milliseconds)
  +0aH     1  bMotorOn     motor-startup time (in 1/8th-second intervals)
          11               length of DisketteParmRec

See Also: Int 13H (disk I/O
          Hard Disk Parameter Table
          Data Structures
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