Table of Contents
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llBl
7625
llB3
llB3
CO 42
llB5
5f
llB6
5E
11 B7
83 C4 06
llBA
l f
llBB
07
llBC
50
llBO
CF
l1BE
l1BE
06 06 07 07 05 05
l1C4
04 05 00 00 00 00
l1CA
00 05 06 0
1 ,
04 04
I 100
04 06 06 04 07 04
11060704
1108
1108
86 16 0463 R
110C
83C206
110F
EC
11 EO
A8 04
11 E2
B4 00
l1E4
74 03
I I E6
E9 128 E R
llE9
I I
E9
A8 02
llEB
75 03
1 I ED
E9 1298 R
llFO
llFO
B4 10
llF2
8B 160463 R
I I
F6
8A C4
11 F8
EE
llF9
42
llFA
50
l1FB
EC
llFC
8A E8
I lFE
58
llFF
4A
1200
FE C4
1202
8A C4
1204
EE
1205
42
1206
EC
1207
8A E5
1209
8A 1 E 0449 R
1200
2A FF
120F
2E: 8A 9F llBE R
1214
2B C3
1216
8B IE 044E R
121A
01 EB
121C
2B C3
121E
7902
1220
2B CO
1222
1222
Bl 03
1224
80 3E 0449 R 04
1229
72 40
122B
80 3E 0449 R 07
1230
74 46
1232
80 3E 0449 R 06
1237
77 28
1239
75 02
1236
01 E8
1230
1230
B2 28
123F
F6 F2
124 I
8A E8
1243
02 ED
1245
8A DC
1247
2A FF
1249
80 3E 0449 R 06
124E
75 04
1250
Bl 04
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
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3162
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C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C+
C
C
C
C
C
C
C
OLD_LP:
JBE
INT
POP
POP
ADD
POP
POP
POP
IRET
READ_LPEN
42H
01
SI
SP,6
OS
ES
BP
; CALL EX I ST I NG CODE
; DISCARD SAVED BX,CX,DX
;
......
-_
............ --
-_
....
--
--_
..
-_
..
--_
..
--_
..
-------
----_
..
-----
---_
..
--
--
---
LIGHT PEN
TH I S ROUT I NE TESTS THE LI GHT PEN SW I TCH AND THE LI GHT
PEN TRIGGER.
IF BOTH ARE SET, THE LOCATION Of THE LIGHT
PEN
IS DETERMINED. OTHERWISE, A RETURN WITH NO
,
INFORMATION IS MADE.
; ON EXIT
;
(AH)
= 0
IF NO LIGHT PEN INFORMATION IS AVAILABLE
;
BX,CX, OX ARE DESTROYED
;
(AH)
= 1 IF LIGHT PEN IS AVAILABLE
;
(DH, DL)
= ROW, COLUMN Of CURRENT LI GHT PEN
;
POSITION
;
(CH)
=
RASTER POS IT I ON (OLD MODES)
;
(CX)
=
RASTER POSITION (NEW MODES)
;
(BX)
=
BEST GUESS AT PIXEL HORIZONTAL POSITION
;
..
-_
....
-
-_
........
-_
....
-_
......
-_
....
-_
..........
---
---_
...
--- ..
----- ...
_-----_
...
_
...... _
..
ASSUME
CS:CODE,DS:ABSO
;----- SUBTRACT_TABLE
VI
LABEL
BYTE
DB
006H, 006H, 007H, 007H, 005H, 005H
DB
004H, 005H, OOOH, OOOH, OOOH, OOOH
DB
OOOH, 005H, 006H, 004H, 004H, 004H
DB
004H, 006H, 006H, 004H, 007H, 004H
DB
007H,004H
PROC
NEAR
;----- WAIT FOR LIGHT PEN TO BE DEPRESSED
MOV
ADD
WIN
IN
TEST
MOV
JZ
JMP
OX, ADDR_6845
DX,6
AL,DX
AL,4
AH,O
V9
V6
;----- NOW TEST FOR LIGHT PEN TRIGGER
0-5
6-B
C-ll
12-17
18-19
GET BASE AODRESS OF 6845
POINT TO STATUS REGISTER
GET STATUS REG I STER
TEST LIGHT PEN SW ITCH
SET NO LIGHT PEN RETURN
CODE
NOT SET, RETURN
C
V9:
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C+
C
C
C
C+
C
C
C
C
C
C
C+
C
C
C+
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
TEST
JNZ
JMP
AL,2
V7A
'V7
;----- TRIGGER HAS BEEN SET, READ THE VALUE IN
V7A:
MOV
AH,16
TEST LI GHT PEN TR I GGER
RETURN WITHOUT RESETT I NG
TR
I
GGER
EXIT LIGHT PEN ROUTINE
;
LIGHT PEN REG I STERS
INPUT REGS POINTED TO BY AH, AND CONVERT TO ROW COLUMN IN OX
MOV
MOV
WOUT
OUT
INC
PUSH
WIN
IN
MOV
POP
DEC
INC
MOV
WOUT
OUT
INC
WIN
IN
MOV
OX, ADDR_6845
AL,AH
DX,AL
OX
AX
AL,DX
CH,AL
AX
OX
AH
AL,AH
DX,AL
OX
AL,DX
AH,CH
; ----- AX HAS THE VALUE READ I N FROM THE 6845
MOV
SUB
MOV
SUB
MOV
SHR
SUB
JNS
SUB
BL, CRT_MODE
BH, BH
BL, CS:Vl [BX]
AX, BX
BX,CRT_START
BX,l
AX,BX
V2
AX,AX
;----- DETERMINE MODE OF OPERATION
ADDRESS REG I STER
REG I STER TO READ
SET I T UP
DATA REGISTER
GET THE VALUE
SAVE IN CX
; ADDRESS REG I STER
SECOND DATA REG I STER
POINT TO DATA REGISTER
GET THE 2ND DATA VALUE
;
IV(
HAS I N PUT VALUE
MODE VALUE TO BX
AMOUNT TO SUBTRACT
TAKE I T AWAY
SCREEN ADDRESS
DIVI DE BY 2
ADJ UST TO ZERO START
IF POSITIVE,
GET MODE
<0 PLAYS AS 0
C
V2:
DETERMI NE MODE
SET *8 SHIFT COUNT
GRAPH I CS OR ALPHA
ALPHA_PEN
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
MOV
CMP
JB
CMP
JE
CMP
JA
JNE
SHR
CL,3
CRT MODE,4
V4 -
CRT_MODE,7
V4
CRT_MODE,06H
V8
V8X
AX,l
; ----- OLD GRAPH I CS MODES
V8X:
MOV
DIV
DL,40
DL
; ----- DETERM I NE GRAPH I CROW POS I T I ON
MOV
ADD
MOV
SUB
CMP
JNE
MOV
CH, AL
CH, CH
BL,AH
BH, BH
CRT MODE,6
V3 -
CL,4
; ALPHA_PEN
DIVISOR FOR GRAPHICS
ROW( AL) AND COLUMN (AH)
AL RANGE 0-99,
AH RANGE 0- 39
SAVE ROW VALUE INCH
*2 FOR EVEN/ODD FIELD
COLUMN VALUE TO BX
*8 FOR MED I UM RES
MEDIUM OR HIGH RES
NOT HIGH RES
SH 1FT VALUE FOR HIGH RES
IBM Enhanced Graphics Adapter 127
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