Int 14/AH=00h

SERIAL - INITIALIZE PORT

AH = 00h
AL = port parameters (see #00300)
DX = port number (00h-03h) (04h-43h for Digiboard XAPCM232.SYS)

Return:
AH = line status (see #00304)
FFh if error on Digiboard XAPCM232.SYS
AL = modem status (see #00305)

Notes: Default handler is at F000h:E739h in IBM PC and 100% compatible BIOSes. Since the PCjr supports a maximum of 4800 bps, attempting to set 9600 bps will result in 4800 bps. Various network and serial-port drivers support the standard BIOS functions with interrupt-driven I/O instead of the BIOS's polled I/O. The 1993/04/08 Compaq system ROM uses only the low two bits of DX. The default setting used by DOS (MS-DOS 6, DR-DOS 7.03, PTS-DOS) when (re-)initializing the serial devices is AL=A3h (2400 bps, no parity, 1 stop bit, 8 data bits).

See Also: AH=04h"SERIAL" - AH=04h"MultiDOS" - AH=05h"SERIAL"

See Also: MEM 0040h:0000h - PORT 03F8h"Serial"


Bitfields for serial port parameters:

Bit(s)  Description     (Table 00300)
7-5    data rate (110,150,300,600,1200,2400,4800,9600 bps)
4-3    parity (00 or 10 = none, 01 = odd, 11 = even)
2      stop bits (set = 2, clear = 1)
1-0    data bits (00 = 5, 01 = 6, 10 = 7, 11 = 8)

See Also: #00302 - #00307 - #00308 - #00309

Category: Serial I/O - Int 14h - S

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