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  Service 03H (decimal 3) was introduced with the PCjr, but has been
  supported in both the PC/AT (in ROM BIOS versions dated 11/15/85 and
  later) and in all PS/2s. It lets you adjust the rate at which the
  keyboard's typematic function operates; that is, the rate at which a
  keystroke repeats automatically while you hold down a key. This service
  also lets you to adjust the typematic delay (the amount of time you can
  hold down a key before the typematic repeat function takes effect).

  To use this service, call interrupt 16H with AH = 03H, and AL = 05H. BL
  must contain a value between 00H and 1FH (decimal 31) that indicates the
  desired typematic rate (Figure 11-3). The value in BH specifies the
  typematic delay (Figure 11-4). The default typematic rate for the PC/AT
  is 10 characters per second; for PS/2s it is 10.9 characters per second.
  The default delay for both the PC/AT and PS/2s is 500 ms.

  --------------------------------------------------------------------------
  00H = 30.0               0BH = 10.9              16H = 4.3
  01H = 26.7               0CH = 10.0              17H = 4.0
  02H = 24.0               0DH = 9.2               18H = 3.7
  03H = 21.8               0EH = 8.6               19H = 3.3
  04H = 20.0               0FH = 8.0               1AH = 3.0
  05H = 18.5               10H = 7.5               1BH = 2.7
  06H = 17.1               11H = 6.7               1CH = 2.5
  07H = 16.0               12H = 6.0               1DH = 2.3
  08H = 15.0               13H = 5.5               1EH = 2.1
  09H = 13.3               14H = 5.0               1FH = 2.0
  0AH = 12.0               15H = 4.6               20H through FFH -
                                                   Reserved
  --------------------------------------------------------------------------

  Figure 11-3.  Values for register BL in keyboard service 03H. The rates
  shown are in characters per second.

  --------------------------------------------------------------------------
  00H = 250
  01H = 500
  02H = 750
  03H = 1000
  04H through FFH - Reserved
  --------------------------------------------------------------------------

  Figure 11-4.  Values for register BH in keyboard service 03H. The delay
  values shown are in milliseconds.