IBM 5150 Technical Reference page 192

laC OBJ LINE SOURCE
5027
J ••• _­ LINE FEED FOUND
5028
F786 5029 UIO:
F786 80FEl8 5030
eMP
DH.24
I BOTTDH OF SCREEN
F789 75E8 5031 JHE
U6
I YES, SCROLL THE SCREEN
H8B Eeee
5032
JMP Ul
; NO. JUST SET THE CURSOR
5033
~
5034 J ----­ BELL FoutI)
5035
F7eD
5036
Ull:
F7eD B302 5037 NOV BL,2 J SET UP COUNT FOR BEEP
F78F E871EE
5038
CAll
BEEP ; Soutl) THE POD BELL
F792 fBDB
5039 JMP US
; TTY_RETURN
5040
WJHTE_TTY ENDP
5041
;---------------------------------------------------------------­
5042
LIGHT PEN
5043 THIS ROUTINE TESTS THE LIGHT PEN SWITCH AND THE LIGHT
5044
PEN TRIGGER. IF BOTH ARE SET, THE LOCATION OF THE lIGHT :
5045 PHI IS DETEIlMINED. OTHERWISE. A RETURN WITH NO
5046 IHFDRHATION IS MADE.
5047 ; ON EXIT
5048
{AH I
=
0 IF NO LIGHT PEN INFORMATION IS AVAILABLE
5049
BX,CX,DX ARE DESTROYED
5050 {AH I
=
1 IF LIGHT PEN IS AVAILABLE
5051 (CH,DLl ::: ROW,COLUHH OF CURRENT LIGHT PEN
5052 POSITION
5053
(CH) ::: RASTER POSITION
5054 (BX) ::: BEST GUESS AT PIXEL HORIZONTAL POSITION :
5055 1------------------------ --------­ - - -­ ---------------------­ ----­
5056 ASSUtlE CS: CODE ,CS:DATA
5057
;----- SUBTRACT_TABLE
F794
soss
VI LABEl
BYTE
F794 03 5059
DB 3,3,5.5.3.3.3.4 •
F795 03
F796 05
F797 05
F798 03
~
F799 03
F79A 03
F79B 04
F79C 5060 READ_LPEN PROC NEAR
5061
5062 ;----- WAIT FOR LIGHT PEN TO BE DEPRESSEO
5063
F79C 8400 5064
"""
AH,O I SET NO LIGHT PEN RETUlN CODE
F79E 8B166300 5065
MOV
OX, ADDR_ 6845 ; GET BASE ADDRESS OF 6845
F7A2 83C206 5066 ADD OX,6 ; POINT TO STATUS REGISTER
F7A5 Et 5067
IH
AL,OX I GET STATUS REGISTER
F7A6 A804
5068 TEST AL,4 ; TEST LIGHT PEN SWITCH
F7A8 757E 5069 JHZ V. I NOT SET, RETURN
5070
5071 1----- NOW TEST
F~ LIGHT PEN TRIGGER
5072
F7AA A802
5073
TEST
AL,2 I TEST LIGHT PEN TRIGGER
F7At 7503
5074 JHZ V7A ; RETURN WITHOUT RESETTING TRIGGER
F7AE E96100 5075
JMP V7
5076
5077 1----- TRIGGER HAS BEEN SET. READ THE VALUE IN
5076
F7ll1
5079 V7A:
F7BI BitlO 5060
NOV
AH,16 ;
LIl~T
PEN REGISTERS ON 6645
5061
5062 ;----- INPUT REGS POINTED TO BY Alt. AND CONVERT TO ROW COLUHN IN ox
5063
F783 88166300 5064
MOV
OX, ADOR_684S ; ADDRESS REGISTER FOR 6845
F787 8AC4 5065
MOV AL.AH
; REGISTER TO READ
F7B9 EE
5080
OUT OX,AL J SET IT UP
r""\ F7BA 42
F7BB EC
5087
5088
IHC
IH
ox
AL.DX
J DATA REGISTER
i
GET THE VALUE
F7BC 8AE8 5089
MOV
CH.AL
; SAVE IN CX
F7BE 4A 5090
DEC
Ox
j
ADDRESS REGISTER
F7BF FEC4 5091
IHe AH
nCI 6AC4 5092 MOV AL,AH I SECOND DATA REGISTER
F7C3 EE
5093
OUT DX,AL
F7C4 42 5094
INC OX
1 POINT TO DATA REGISTER
F7C5 EC 5095
IH
AL,DX I GET SECOND DATA VALUE
F7C6 8AE5 5096
MOV
AH,CH I AX HAS INPUT YALUE
System BIOS 5-99