IBM XT 5160 Technical Reference page 206

OUTPUT
AX MOD I F I ED ACCORD I NG TO PARAMETERS OF CALL
ALL OTHERS UNCHANGED
5-59
10 - 1 BITS
11 - 8 BITS
o -
1
1 - 2
I NTERRUPTS BACK ON
SAVE SEGMENT
I RETURN TO CALLER, NO ACT I ON
CHECK FOR ADAPTER NUMBER VALID 0-3
ERROR EX I T I F OUT OF RANGE
RS232 VALUE TO (S I)
AND TO (01) (FOR TIMEOUTS)
WORD OFFSET
GET BASE ADDRESS
TEST FOR 0 BASE ADDRESS
RETURN
TEST FOR (AH) = OOH
COMMO I NIT I ALI ZA T I ON
TEST FOR (AH) = 0 I H
SEND (AL)
TEST FOR (AH)= 02H
RECEIVE INTO (AL)
TEST FOR (AH) = 03H
ERROR I F BAD COMMAND
COMMUN I CAT I ON STATUS
I SET ERROR RETURN CODE
RETURN FROM RS232
XO - NONE
01 - ODD
11 - EVEN
RS232 (01/10/86)
1-1
01-10-86
000 - 110
001 - 150
010 - 300
011 - 600
100 - 1200
101 - 2400
110 - 4800
111 - 9600
ON RETURN, CONDITIONS SET AS IN CALL TO COMMO STATUS (AH=03H)
( AH ) = 0 I H SEND THE CHARACTER IN (AL ) OVER THE COMMO LINE
(AL) REG I STER I S PRESERVED
ON EX IT, BIT 1 OF AH I S SET I F THE ROUTI NE WAS UNABLE TO
TO TRANSM I T THE BYTE OF OAT A OVER THE LINE.
IF BIT 1 OF AH I S NOT SET, THE
REMA I NDER OF (AH) I S SET AS I N A STATUS REQUEST,
REFLECTING THE CURRENT STATUS OF THE LINE.
(AH) = 02H RECE I VE A CHARACTER IN (AL) FROM COMMO LINE BEFORE
RETURN I NG 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 (1,4,3,2, 1 )
IF (AH) HAS BIT 1 ON (TIME OUT) THE REMAINING
BITS ARE NOT PRED I CT ABLE.
THUS, ( AH) I S NON ZERO ONLY WHEN AN ERROR OCCURRED.
(AH) = 03H RETURN THE COMMO PORT STATUS IN (AX)
(AH) CONTAINS THE LINE CONTROL STATUS
BIT 1 = T I ME OUT
BIT 6 = TRANSM I T SH I FT REG I STER EMPTY
BIT 5 = TRANSM I T HOLD I NG REG I STER EMPTY
BIT 4 = BREAK DETECT
BIT 3 = FRAMING ERROR
BIT 2 = PARITY ERROR
BIT 1 = OVERRUN ERROR
BIT 0 = DATA READY
(ALl CONTA I NS THE MODEM STATUS
BIT 1 = RECE I VE LI NE SIGNAL DETECT
BIT 6 = RING INDICATOR
BIT 5 = DATA SET READY
BIT 4 = CLEAR TO SEND
BIT 3 = DELTA RECE I VE LI NE SIGNAL DETECT
BIT 2 = TRA ILl NG EDGE RING DETECTOR
BIT 1 = DELTA DATA SET READY
BIT 0 = DELTA CLEAR TO SEND
(OX) = PARAMETER INDICATING WHICH RS232 CARD (0,1 ALLOWED)
DA TA AREA ORS232 BASE CONTA I NS THE BASE ADDRESS OF THE 8250 ON THE CARD
LOCATI ON 400H CONTA I NS UP TO 4 RS232 ADDRESSES POSS I BLE
DATA AREA LABEL ORS232 TIM OUT (BYTE) CONTAINS OUTER LOOP COUNT
VALUE FOR TIMEOUT (DEFAULT'; 1 )
I NT 14 H ------------------------------------------------------------------
RS232 10 I
- TH I S ROUT I NE PROV I DES BYTE STREAM I/O TO THE COMMUN I CAT IONS I
PORT ACCORD I NG TO THE PARAMETERS:
I
I
(AH) = OOH INITIALIZE THE COMMUNICATIONS PORT
I
(AL) HAS PARAMETERS FOR INITIALIZATION
I
I
1 6 5 4 3 2 1 0
I
----- BAUD RATE -- -PAR I TY-- STOPB I T --WORD LENGTH--,
I
PAGE 118,121
TITLE RS232 ---- 01/10/86 COMMUNICATIONS BIOS (RS232)
.LIST
CODE SEGMENT BYTE PUBL I C
PUBLIC RS232 10 1
EXTRN A I : NEAR -
EXTRN DDS: NEAR
ASSUME
CS:CODE,DS:DATA
0000 RS232 - 10 1 PROC FAR
0000 FB STI
000 I IE PUSH OS
0002 52 PUSH OX
0003 56 PUSH SI
0004 51
PUSH
01
0005 51 PUSH CX
0006 53 PUSH BX
0001 83 FA 03 CMP DX,03H
OOOA 11 24 JA A3E
OOOC 8B F2 MOV SI,DX
OOOE 8B FA MOV DI,DX
0010 01 E6 SHL SI,I
0012 E8 0000 E CALL DDS
0015 8B 94 0000 R MOV OX, ORS232_BASE [S I]
0019 OB 02 OR DX,DX
OOIB 14 13 JZ A3E
0010 OA E4
OR
AH,AH
00 IF 14 18 JZ A4
0021 FE CC DEC AH
0023 14 4B JZ A5
0025 FE CC DEC AH
0021 14 10 JZ AI2
0029 A2:
0029 FE CC DEC AH
002B 15 03 JNZ A3E
0020 E9 OOBB R
JMP A18
0030 A3E:
0030 B4 80
MOV AH,080H
0032
A3:
0032 5B POP BX
0033 59 POP CX
0034 5F POP 01
0035 5E POP S I
0036 5A POP OX
0031 IF
POP
OS
0038 CF
IRET
I
2
3
4 0000
5
6
7
8
9
10
11
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14
15
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19
80
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91
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101
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I 10
III
112
113
114
IBM Personal Computer MACRO Assembler Version 2.00
RS232 ---- 01/ 10/86 COMMUNICATIONS BIOS (RS232)