INT E0 - DR Multiuser DOS - "P_DELAY" - DELAY EXECUTION
        CL = BDh
        DX = delay in system ticks
Return: after the delay elapses
Notes:  the length of a system tick is installation-dependent (typically
          1/50 or 1/60 second); the length may be determined by reading the
          TICKSPERSEC value from the system data segment
        the actual delay before the process is rescheduled to run may be up to
          one tick longer than requested; the delay between rescheduling and
          actual execution cannot be predicted if higher-priority processes
          are awaiting a turn at the CPU