Int D4 Fn 07  - Pc-mos/386 V3.0+ - Wait For Event                          [O]

   AH = 07h
   AL = events to monitor (see #3686)
   BX = number of timer ticks until timeout if AL bit 1 set
   CX = bitmap of IRQs to monitor if AL bit 2 set
       (bit 0 = IRQ0 .. bit 15 = IRQ15)
   DX = port to monitor if AL bit 3 set

Return: CF clear if successful
       AL = type of event which woke up task (see #3686)
       CX = IRQ (if any) which awakened task
       DX = port (if any) which awakened task
   CF set on error
       AX = error code (see #1366 at INT 21/AH=59h/BX=0000h)

Note:  a device driver may make this call with AL=00h, which indicates that
     the driver is responsible for setting and clearing the TCBWAIT field
     in the TCB.  To put task to sleep, set TCBWAIT bits 2-0 to 001; to
     reawaken it, set bit 1 (leaving other bits unchanged)

See Also: AH=04h,INT 16/AH=00h,INT 38

Bitfields for PC-MOS/386 events to monitor:
Bit(s) Description (Table 3686)
 0 keystroke
 1 timeout
 2 IRQ
 3 port access
 7 return status of user poll routine (other ignored if set)