Get port configuration Entry: AH = 7Ch Return: AH = port number AL = baud rate 00h = 50 baud 01h = 75 baud 02h = 110 baud 03h = 134.5 baud 04h = 150 baud 05h = 300 baud 06h = 600 baud 07h = 1200 baud 08h = 1800 baud 09h = 2000 baud 0Ah = 2400 baud 0Bh = 4800 baud 0Ch = 7200 baud 0Dh = 9600 baud 0Eh = 19200 baud