Texas Instruments 990 Installation And Operation Manual page 50

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945423-9701
3.6.8 CLEAR SCREEN. The following code sequence clears the screen by filling it with blanks.
Rl
R2
R12
KBASE
WRDSEL
SCRSIZ
VIDENB
DTASTB
CURSOZ
CLEAR
CLR002
EQU
EQU
EQU
DATA
EQU
EQU
EQU
EQU
EQU
EQU
MOV
SBO
LI
LDCR
LI
SBZ
SBZ
LDCR
SBO
SBZ
DEC
JNE
SBO
1
2
12
>80
>F
1920
>E
>8
>A
$
@KBASE,RI2
WRDSEL
Rl, >2000
Rl, 11
R2, SCRSIZ
WRDSEL
VIDENB
RI,8
DTASTB
CURSOR
R2
CLROO2
VIDENB
3-18
Workspace register 1
Workspace register 2
Workspace register 12
Keyboard character base
Select word (0=0; 1=1).
Screen size = 1920 characters.
Display enable.
Data strobe
Move cursor.
Transfer keyboard character base to
workspace register 12.
Select word 1.
Home cursor.
Load screen size into R2.
Select word O.
Disable video.
Strobe data to CRT.
Increment cursor address.
Decrement screen size.
Loop.
Enable video.
Digital Systems Division