Int 14 Fn 22  - Multidos Plus - Receive Character                          [S]

   AH = 22h
   DX = port number

Return: AH = status (see also AH=21h"MultiDOS")
       00h successful
       AL = character
       3Dh framing and parity error
       3Eh overrun error
       3Fh framing error
       40h parity error
       96h ring buffer overflow

Note:  if no character is available, this function waits until a character
     arrives or an implementation-dependent timeout elapses

See Also: AH=20h"MultiDOS",AH=21h"MultiDOS",AH=27h