IBM 5150 Technical Reference page 145

LOC OBJ LINE SOURCE
E767 IF
E768 CF
E769
E769 8AEO
E768 83C203
E76E B080
E770 EE
E771 8A04
E773 BI04
E775 02C2
E777 81E20EOO
E77B BF29E7
E77E D3FA
E780 8814
E782 42
E783 2E8A4501
E787 EE
E788 4A
E789 2E8A05
E78C EE
E780 83C203
E790 8A.C4
E79Z 241F
E794 EE
E795 4A
E796 4A
E797 BODO
E799 EE
E79A E849
E79C
E79C 50
E790 83C204
E7AO B003
E7A2 EE
E7A3 42
E7A4 42
E7A5 8730
E7A7 E84800
E7AA 7408
E7AC
E7AC 59
E7AD 8ACl
E7AF
E7AF 80ce80
E782 EBAE
E7B4
E784 4A
E785
E7B5 8720
E7B7 E83800
E7BA 75FO
E7BC
E7BC 63EA05
E7BF 59
E7CO 8ACI
E7C2 EE
E7C3 E890
E7C5
E7C5 83C204
E7C8 8001
E7CA EE
E7CB 42
E7ee 42
E7CD
E7CD BnD
1662 pop OS
1663
IRET
I
RETURN TO CALLER. NO ACTION
1664
1665 1----- INITIALIZE THE COtH.tUtATIONS PORT
1666
1667 A4:
1668
MOV
AH,AL
; SAVE INIT PARMS IN AH
1669
ADD OX,l
I POINT TO 8250 CONTROL REGISTER
1670
MOV
AL,60H
1671 OUT aX,AL
; SET OLAB=1
1672
1673 ;----- DETERMINE BAUD RATE DIVISOR
1674
1675 MDV
Ol,AH I GET PARMS TO 0 l
1676
MOV Cl,4
1677
ROL Dl,Cl
1678 AND
DX,OEH ; ISOLATE THEM
1679 MDV
OI,OFFSET Al
I
BASE OF TABLE
1680
ADD
OI,DX ; PUT INTO INDEX REGISTER
1681
MDV OX, RS232_BASE [SI 1
I POINT TO HIGH ORDER OF DIVISOR
1682
INC
OX
1683 MDV
Al,CS:(DI1+l ; GET HIGH ORDER OF DIVISOR
1684 OUT
DX,Al
I
SET MS OF DIV TO 0
1685 DEC
OX
1686 MOV
Al,CS:(DIl
1
GET lOW ORDER OF DIVISOR
1687
OUT
DX,Al
i SET lOW OF DIVISOR
1688
ADD DX,3
1689 MOV
Al,AH
; GET PARMS BACK
1690
AND
Al,OlFH ; STRIP OFF THE BAUD BITS
1691
OUT
DX,Al
; lINE CONTROL TO 8 BITS
1692
DEC OX
1693
DEC OX
1694
MDV Al,O
1695
OUT DX,Al
; INTERRUPT ENABLES All OFF
1696
JMP
SHORT Al8
I
COM_STATUS
1697
1698
1-----
SEND CHARACTER IN (All OVER CoMMo lINE
1699
1700 AS:
1701 PUSH AX
1 SAVE CHAR TO SEND
1702
ADD DX.4 ; MODEM CONTROL REGISTER
1703 MOV Al.3 ; DTR AND RTS
1704
OUT DX.Al ; DATA TERMINAL READY, REQUEST TO SEND
1705
INC OX ; MODEM STATUS REGISTER
1706 INC OX
1707 MoV SH,30H
I
DATA SET READY & CLEAR TO SEND
1708
CALL WAITJOR_STATUS I ARE BOTH TRUE
1709 JE A9 ; YES, READY TO TRANSMIT CHAR
1710 A7:
1711
pop
CX
1712 MOV
I RELOAD DATA BYTE
1713 AS:
1714
OR
AH.80H I ItIlICATE TIME OUT
1715 JMP
Al ; REnJRN
1716 A9:
; ClEAR_TO_SEND
1717 DEC
OX ; lINE STATUS REGISTER
1718 AID:
; WAIT_SEND
1719 MOV BH,20H
I IS TRANSMITTER READY
1720
CAll WAITJOR_STATUS
I TEST FOR TRANSMITTER READY
1721
JNZ A7 I RETURN WITH TIME OUT SET
1722
All:
; OUT_CHAR
1723
SUB J DATA PORT
1724
POP ; RECOVER IN CX TEMPORARILY
1725 MDV
I MOVE CHAR TO Al FOR OUT, STATUS IN AH
1726 OUT
I OUTPUT CHARACTER
1727
JMP
I
RETURN
1728
1729
1-----
RECEIVE CHARACTER FROM CoMMo lINE
1730
1731 A12:
1732
ADD
OX,4
I
MODEM CONTROL REGISTER
1733 MOV Al,l
I
DATA TERMINAL READY
1734 OUT
DX.Al
1735
INC
OX 1
MODEM STATUS REGISTER
1736 INC OX
1737 A13: ; WAIT_DSR
1738
MOV
BH,20H
I
DATA SET READY
5-52 System BIOS