INT 14H 00H: Initialize Asynchronous Communication Port

 Expects: AH    00H
          AL    initialization bit flags (see below)
          DX    COMM port number (0 to 3)
          ──────────────────────────────────────────────────────────────────
 Returns: AH    line status  ═╦══► see BIOS COM status codes
          AL    modem status ═╝
          ──────────────────────────────────────────────────────────────────
    Info: Sets the speed, word length, etc for the specified COM port.

       AL on entry, AL specifies the COM settings:

          ┌7┬6┬5┬4┬3┬2┬1┬0┐
          │baud │par│s│len│
          └─┴─┴─┴─┴─┴╥┴─┴─┘ bit  mask
           ╚═╦═╝ ╚╦╝ ║ ╚═╩═►0-1: 03H  word length: 10=7 bits; 11=8 bits
             ║    ║  ╚═════►  2: 04H  stop bits:  0=1; 1=2;
             ║    ╚════════►3-4: 18H parity code: x0=none; 01=odd; 11=even
             ╚═════════════►5-7: e0H baud rate  000=110; 100=1200
                                                001=150; 101=2400
                                                010=300; 110=4800
                                                011=600; 111=9600

   Notes: BIOS does not support speeds beyond 9600 baud, even though most
          hardware is capable of much higher rates.

See Also: INT 14H: Serial Port I/O
          Asynchronous Adapter Ports
          BIOS Data Area
          ROM-BIOS Functions
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