{{page>en:templates:biosint}}

====== Int 14H, AH=00H ======

===== Version =====

IBM 5150 and higher

===== Brief =====

Initialize serial port

===== Family API =====

[[en:docs:fapi:DosDevIOCtl]]

===== Input =====

  * 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)

===== Macro =====

<code asm>
INCLUDE BIOS.INC

@AuxInit 0, A3H
</code>

===== 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).

===== Note =====

Text based on [[http://www.cs.cmu.edu/~ralf/files.html|Ralf Brown Interrupt List Release 61]]

{{page>en:templates:biosapi}}

{{page>en:templates:fapi}}