IBM PC CONVERTIBLE User Manual

Communications Interrupt Hex 14
(COMMO_IO)
; -----INT 14H --------------------------------------------------------
COMMO_IO
THIS ROUTINE PROVIDES BYTE STREAM I/O TO THE COMMUNICATIONS
PORT ACCORDING TO THE PARAMETERS:
(AH)~O INITIALIZE THE COMMUNICATIONS PORT
(AL) HAS PARAMETERS FOR INITIALIZATION
7 6 5
----- BAUD RATE --
000 - 110
001 - 150
010 - 300
011 - 600
100 - 1200
101 - 2400
110 - 4800
111 - 9600
4 3
-PARITY--
XO - NONE
01 - ODD
11 - EVEN
2
STOP BIT
o - 1
1 - 2
1 0
--WORD LENGTH-
10 - 7 BITS
11 - 8 BITS
ON RETURN, CONDITIONS SET AS IN CALL TO COMMO STATUS (AH~3)
(AH)~l SEND THE CHARACTER IN (AL) OVER THE COMMO LINE
(AL) REGISTER IS PRESERVED
ON EXIT, BIT 7 OF AH IS SET IF THE ROUTINE WAS UNABLE
TO TRANSMIT THE BYTE OF DATA OVER THE LINE.
I F
BIT 7 OF AH IS NOT SET, THE REMAINDER OF AH
IS SET AS IN A STATUS REQUEST, REFLECTING THE
CURRENT STATUS OF THE LINE.
(AH)~2 RECEIVE A CHARACTER IN (AL) FROM COMMO LINE BEFORE
RETURNING TO CALLER
ON EXIT, AH HAS THE CURRENT LINE STATUS, AS SET BY THE
THE STATUS ROUTINE, EXCEPT THAT THE ONLY BITS
LEFT ON ARE THE ERROR BITS (7,4,3,2,1)
IF AH HAS BIT 7 ON (TIME OUT) THE REMAINING
BITS ARE NOT PREDICTABLE.
THUS, AH IS NON ZERO ONLY WHEN AN ERROR
OCCURRED.
(AH)~3 RETURN THE COMMO PORT STATUS IN (AX)
AH CONTAINS THE LINE STATUS
BIT 7 ~ TIME OUT
BIT 6 ~ TRANS SH I FT REGISTER EMPTY
BIT 5 ~ TRAN HOLDING REGISTER EMPTY
BIT 4 ~ BREAK DETECT
BIT 3 ~ FRAMING ERROR
BIT 2 ~ PARITY ERROR
BIT 1 ~ OVERRUN ERROR
BIT 0 ~ DATA READY
AL CONTAINS THE MODEM STATUS
BIT 7 ~ RECEIVED LINE SIGNAL DETECT
BIT 6 ~ RING INDICATOR
BIT 5 ~ DATA SET READY
BIT 4 ~ CLEAR TO SEND
BIT 3 ~ DELTA RECEIVE LINE SIGNAL DETECT
BIT 2 ~ TRAILING EDGE RING DETECTOR
BIT 1 ~ DELTA DATA SET READY
BIT 0 ~ DELTA CLEAR TO SEND
(AH) ~OTHER
NO ACTI ON TAKEN.
(DX) ~ PARAMETER INDICATING WHICH RS232 CARD (0,1 ALLOWED)
DATA AREA RS23LBASE CONTAINS THE BASE ADDRESS OF THE 8250 ON THE
CARO. LOCATION 400H CONTAINS UP TO 4 RS232 ADDRESSES POSSIBLE.
DATA AREA LABEL RS23LTIILOUT (BYTE) CONTAINS OUTER LOOP COUNT
VALUE FOR TIMEOUT (DEFAULT~l).
REGISTERS MODIFIED
AX MODIFIED ACCORDING TO PARMS OF CALL
ALL OTHERS UNCHANGED
2-144 ROM BIOS

IBM PC CONVERTIBLE Specifications

General

Brand	IBM
Model	PC CONVERTIBLE
Category	Laptop
Language	English