AH = 14h: Wait for Keyboard Event, Variable Timeout

This function is identical to Fcn 13h, except that it supports a variable timeout. The timeout value is in units of "Timer0 Ticks", or roughly 55 msec units. If the Timeout value is 0, the routine will return immediately if a key or shift-status change is not detected.

• Input: AH = 14h
  BX = Current kbd shift flags (same format as service 12h)
  CL = Timeout (55 msec units)

• Output: Zero flag is clear if character is available
  AH = Scancode
  AL = ASCII character code, or
  00h for a special scancode, or
  Zero flag is set if timeout or keyboard flags changed
  AX is loaded with the keyboard flags as described in service 12h.

• Error conditions: None
• Registers Modified: AX, FLAGS