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  Description:  Extended Initialize Communications Port      [PS/2]
 
  Initializes a serial communications port to a desired baud rate, parity,
  word length, and number of stop bits. Provides a superset of Int 14H
  Function 00H capabilities for PS/2 machines.
 
  Input                                  Output
  ═══════════════════════════            ═════════════════════════════
  AH=04H                                 AH=port status
  AL=break flag                             (see Int 14H Function 00H)
     00H no break                        AL=modem status
     01H break                              (see Int 14H Function 00H)
  BH=parity
     00H none
     01H odd
     02H even
     03H stick parity odd
     04H stick parity even
  BL=stop bits
     00H 1 stop bit
     01H 2 stop bits if
         word length=6-8 bits
     01H 1.5 stop bits if
         word length=5 bits
CH=word length
     00H 5 bits
     01H 6 bits
     02H 7 bits
     03H 8 bits
  CL=baud rate
     00H 110 baud
     01H 150 baud
     02H 300 baud
     03H 600 baud
     04H 1200 baud
     05H 2400 baud
     06H 4800 baud
     07H 9600 baud
     08H 19,200 baud
  DX=communications port number
     (0=COM1, 1=COM2,   etc.)
                                    -♦-