IBM 5150 Hardware Reference Manual page 215

LaC OBJ
LINE SOURCE
E7SF
1505 .402:
E7SF FEee
1506
DEC AH ; TEST FOR (AH )=3
£761 7503 1507
JHZ A3
£763 £98900
1508 JMP A18
; COMMUNICATION STATUS
£766
1509 .403:
, RETURN FROM RS232
E766 59 1510 POP
ex
£767 SF 1511 POP 01
E768 5E
1512
POP
51
£769 SA 1513 POP DX
E76A IF 1514 POP
as
E768 CF
1515 lRET I RETURN TO CAllER. NO ACTION
1516
1517 ;------ INITIALIZE THE COMM\.JHICATlONS PORT
1518
£76C 1519
A4:
f76C 8AEO
1520 NOV AH.Al ; SAVE INIT PARMS IN AH
£76E 83C203
1521 ADD OX,3 • POINT TO 8250 CONTROL REGISTER
E771 B080
1522
ti0V
.4.L,6QH
E773 EE 1523 OUT OX.Al ; SET DLAS;1
1524
1525
; -----­ DETERMINE BAUD RATE DIVISOR
1526
£774 8A04 152:7
MaV
OL.AH ; GET PARMS TO DL
£776 00C2 1528
ROL OLd
E778 00C2 1529
ROL OLd
I
GET BAUD RATE TERM TO LOW
BITS
E77A DOC2
1530 ROL OLd
Ene ooe2
1531 ROL
OL,}
; *2 FOR WORD TASlE ACCESS
EnE 81E20EOO 1532
A,m
OX.DEH ; ISOLATE THEM
£782 SF29E7
1533
MOV
01.0FFSET Al
I
BASE OF TADlE
E78S 03FA
1534 ADO OI.DX ; PUT INTO INDEX REGISTER
E787 88940000 1535 MOV OX.RS232_BASE(SIl ; POINT TO HIGH ORDER OF DIVISOR
E7BB 42 1536
INC
OX
E7SC 2E8A4501 1537
NOV
Al,CS:[DI1+l ; GET HIGH ORDER OF DIVISOR
£790 EE
1538
OUT
OX.AL
; SET MS OF DIV TO 0
E791 4" 1539
DEC
OX
E792 2£8A05
1540 HOV Al.CS:[OIl ; GET LOW ORDER OF DIVISOR
E795 EE 1541 OUT OX.Al ; SET LOW OF DIVISOR
£796 83C203 1542
ADO
DX.3
£799 8'&'C4 1543 MOV AL.AH ; GET PARMS BACK
£798 241F 1544
' N O
AL.OIFH ; STRIP OFF THE BAUD BITS
£790 EE 1545
OUT DX,At
; LINE CONTROL TO 8 BITS
£79£ 83£A02
1546
SUB
DX,2
f7Al BODO 1547 MOV Al,O
£7A3 EE 1546 OUT DX,Al J INTERRUPT ENABLES ALL OFF
£7A4 E879 1549
JMP SHORT .1.18 ; Cot'CSTATUS
1550
1551 ,------ SEND CHARACTER IN (ALI OVER COMMa LINE
1552
£7A6
1553 AS:
E7A6 50 1554
PUSH AX I SAVE CHAR TO SEND
£7A7 83C204
1555 ADD OX.4 ; MODEM CONTROL REGISTER
E7AA 8003 1556
MOV AL.3 ; OTR AND RTS
E7AC EE
1557
OUT OX.AL ; DATA TERMIN'AL READY, REQUEST TO SEND
£7AO 33C9 1558
XOR
cx.cx
; INITIALIZE TIME OUT COUNT
E7AF 83C202 1559 ADD
DX.2 ; MODEM STATUS REGISTER
E7BZ 1560
.4.6:
I
WAIT_OATA_SET_READY
£782 EC
1561 IN At.OX ; GET HOOEN STATUS
E7B3 .l820 1562 TEST Al.20H ; DATA SET READY
E7BS 7508 1563 Jt~Z A7
I
TEST_CLEAR_TO_SEND
£7B7 E2F9 1564
LOOP A6 ; WAIT_OATA_SET_READY
E7B9 58 1565 POP AX
E7BA 80CC50 1566
OR AH.80 ; INDICATE TINE OUT
E7BD fBA7
1567 JMP A3 I RETURN
E7SF
1568
A7:
E7SF 28C9 1569
SUB
cx.CX
E7et 1570 A8:
; WAIT_CLEAR_TO_SEHO
E7et EC
1571
IN Al.DX ; GET MODEM STATUS
E7t2 A810
1572 TEST Al.IOH I TEST CLEAR TO SEND
E7C4 7508
1573 JHZ A9
£7&6 E2F9­ 1574 LOOP A6 ; W.6.IT_tlE.6.R_TO_SEND
£7C8 58
1575
pop AX
, TIME OUT HA.S OCCURRED
£7C9 80ce80
1576 OR AH.80H
E7ee £B98 1577 JMP A3 ; RETLlR~1
f7eE
1578
.4.9:
f7eE 4A 1579 DEC
ox
; LINE STATUS REGISTER
E7CF 2BC9 1580
SUB
CX.CX
; ItUTIALIZE WAIT COUNT
E701 1581 AlD:
A-22