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LaC OB.JECT
LINE
SOURCE
(BIOS FOR THE IBM PERSONAL COMPUTER XT)
I I /08/82
IS TH IS BW CARD
IS THIS GRAPHICS
IS TH I S GRAPH I CS
IS TH I S BW CARD
WR I TE AC CaNT I NUE
GET ATTRIBUTE TO AH
SAVE ON STACK
SAVE WR I TE COUNT
ADDRESS TO 0 I REG I STER
WR ITE COUNT
CHARACTER
IN BX REG
WR I TE_LOOP
GET BASE ADDRESS
POINT AT STATUS PORT
READ_AC_CONT I NUE
ESTABLISH ADDRESSING IN SI
NO PAGE
DETERM I NE LOCA T I ON I N REGEN
ADD TO START OF REGEN
GET BASE ADDRESS
POINT AT STATUS PORT
GET STATUS
I S IT LOW
WAIT UNTIL IT IS
NO MORE INTERRUPTS
GET STATUS
I S IT HIGH
WA I T UNTI LIT IS
RECOVER THE CHAR / ATTR
PUT THE CHAR / ATTR
I NTERRUPTS BACK ON
AS MANY TIMES AS REQUESTED
GET SEGMENT FOR QU I CK ACCESS
WA I T FOR RETRACE LOW
GET STATUS
I S HaRZ RETRACE LOW
WA I T UNT I LIT IS
NO MORE INTERRUPTS
WA I T FOR RETRACE HIGH
GET STATUS
IS IT HIGH
WA I T UNTI LIT IS
GET THE CHAR / ATTR
; 0 I SPLA Y PAGE TO CX
NEAR
PROC
CL,BH
CH,CH
S I , CX
; MOVE TO S I FOR
INDEX
S I , I
;
• 2 FOR WORD OFFSET
AX,[SI+OFFSET CURSOR POSN]
; GET ROW/COLUMN OF THAT PAGE
BX ,BX
-
;
SET START ADDRESS TO ZERO
P5
; NO PAGE
; PAGE LOOP
; LENGTH OF BUFFER
FIND POSITION
SI,BX
AL,DX
AL, I
P3
AL,DX
AL,I
P9
AX,BX
BX,CRT LEN
P4
-
AH,BL
AX
CX
F I NO pas I TI ON
DI,BX
CX
BX
pas I TION
BX,AX
ENDP
( AL )
=
CHAR READ
( AH )
=
ATTR IBUTE READ
ADD
LOOP
CALL
MOV
MOV
PUSH
PUSH
CALL
MOV
POP
POP
INPUT
WR I TE AC CURRENT
-THIS ROUT I NE WR I TES THE ATTR IBUTE
AND CHARACTER AT THE CURRENT CURSOR
pas IT ION
(AH)
=
CURRENT CRT MODE
(BH)
=
DISPLAY PAGE
(CX)
=
COUNT OF CHARACTERS TO WR I TE
(ALl
=
CHAR TO WR I TE
(BLl
=
ATTR IBUTE OF CHAR TO WR I TE
(OS)
=
DATA SEGMENT
(ES)
=
REGEN SEGMENT
OUTPUT
NONE
(AH)
=
CURRENT CRT MODE
(BH)
=
0 I SPLA Y PAGE ( ALPHA MODES ONLY)
(OS)
=
DATA SEGMENT
; OUTPUT
(ES)
=
REGEN SEGMENT
;----- WAIT FOR HORIZONTAL RETRACE
;----- WAIT FOR HORIZONTAL RETRACE
.
-------------------------------------------------------
; READ AC CURRENT
;
-
TH I S ROUT I NE READS THE ATTR IBUTE AND CHARACTER
;
AT THE CURRENT CURSOR pas I T I ON AND RETURNS THEM
; I NPUT
TO THE CALLER
.------------------------------------------------
WR I TE AC CURRENT
PROC
NEAR
-
CMP
AH,4
.JC
P6
CMP
AH,7
.JE
P6
.JMP
GRAPHICS_WRITE
MOV
OX, ADDR_6845
ADD
DX,6
PUSH
ES
POP
OS
P2:
IN
AL,DX
TEST
AL, I
.JNZ
P2
CLI
IN
TEST
.JZ
MOV
STOSW
STI
LOOP
P7
.JMP
V IDEO RETURN
WRITE_AC_CURRENT
-
ENDP
MOV
OX, ADDR_6845
ADD
DX,6
P8:
IN
AL,DX
TEST
AL,
I
.JNZ
P8
CLI
P9:
F I NO pas I TI ON
-
MOV
XOR
MOV
SAL
MOV
XOR
.JCXZ
CALL
ADD
RET
FIND_pas I T ION
ASSUME
CS:CODE,DS:DATA,ES:DATA
READ AC CURRENT PROC
NEAR
-
-CMP
AH,4
.JC
PI
CMP
AH,7
.JE
PI
.JMP
GRAPHICS_READ
IN
TEST
.JZ
LODSW
.JMP
VIDEO_RETURN
READ_AC_CURRENT ENDP
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
PI:
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
P3:
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
P4:
3994
3995
3996
P5:
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
40 I 0
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
P6:
4024
4025
4026
4027
4028
4029
4030
4031
P7:
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
F39E
F39E 8ACF
F3AO 32ED
F3A2 8BFl
F3A4 0 I E6
F3A6 8B4450
F3A9 33DB
F3AB E306
F3AD
F3AD 031 E4COO
F3BI E2FA
F3B3
F3B3 E8CFFE
F3B6 0308
F3B8 C3
F374
F374 80FC04
F377 7208
F379 80FC07
F37C 7403
F37E E9A802
F381
F381 E81 AOO
F384 8BF3
F3D 1 8B166300
F3D5 83C206
F3D8
F3D8 EC
F3D9 A801
F3DB 75FB
F3DD FA
F3DE
F3DE EC
F3DF A80 I
F3El
14FB
F3E3 8BC3
F3E5 AB
F3E6 FB
F3E7 E2E8
F3E9 E9D9FD
F3B9
F3B9 80FC04
F3BC 7208
F3BE 80FC07
F3Cl
7403
F3C3 E9B20 I
F3C6
F3C6 8AE3
F3C8 50
F3C9 51
F3CA E8DIFF
F3CD 8BFB
F3CF 59
F3DO 5B
F3DI
F386 8B166300
F38A 83C206
F38D 06
F38E IF
F38F
F38F EC
F390 A80 I
F392 75FB
F394 FA
F395
F395 EC
F396 A80 I
F398 14FB
F39A AD
F39B E927FE
5-156
PC-XT System BIOS (11/08/82)
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