INT 14,0 - Initialize Communications Port Parameters
AH = 00 AL = parms for initialization (see tables below) DX = zero based serial port number (0-1) (0-3 for AT) │7│6│5│4│3│2│1│0│ AL Parity (bits 4 & 3) │ │ │ │ │ │ └─┴──── word length bits 00 = none │ │ │ │ │ └─────── stop bits flag 01 = odd │ │ │ └─┴──────── parity bits 10 = none └─┴─┴─────────── baud rate bits 11 = even Word length (bits 1 & 0) Stop bit count (bit 2) 10 = 7 bits 0 = 1 stop bit 11 = 8 bits 1 = 2 stop bits Baud rate (bits 7, 6 & 5) 000 = 110 baud 100 = 1200 baud 001 = 150 baud 101 = 2400 baud 010 = 300 baud 110 = 4800 baud 011 = 600 baud 111 = 9600 baud (4800 on PCjr) on return: AH = port status AL = modem status - for status bits see INT 14,STATUS