Radio Shack TRS-80 model III Owner's Manual page 116

DISK BASIC
7D00 21003C
7D03 3GBF
7D05 11013C
7D08 01FF03
7D0B EDB0
7D0D C3
7D00
0(3230
ZAP
00240
00250
002G0
00270
00280
5
00290
00300
LD
LD
LD
LD
LDIR
RET
END
HLtVIDEO
(HL)
,
WHITE
DEtVIDEO+1
BC»C0UNT
?AP
5SOURCE ADDRESS
iPUT OUT 1ST
BYTE
^DESTINATION ADDRESS
5NUMBER OF
ITERATIONS
5DO IT
TO
IT!
!
!
iRETURN TO BASIC
This routine
can be pokec!
into
ram
and
accessed
as
a
usr
routine. First start
basic
and answer
the
MEMORY SIZE question with
31999.
Then
run
the
program.
100
'
PROGRAM: USR1
110 '
EXAMPLE
OF
A
USER MACHINE LANGUAGE FUNCTION
115
'
DEPRESS THE '(§'
KEY WHILE
NUMBERS ARE
PRINTING
TO
STOP
120
'
130
/
*******
POKE MACHINE PROGRAM INTO MEMORY *******
140
'
150
DEFUSR1
=
&H7D00
1S0
FOR
X
=
32000 TO
32013 '7D00 HEX
EQUAL 32000 DECIMAL
170
READ
A
180
POKE
X*
A
190
NEXT
X
192 '
194
'
******* CLEAR SCREEN
&
PRINT NUMBERS
1
THRU
100
*******
195
'
200 CLS
205 PRINT TAB* 15)5
"WHITE-OUT USER ROUTINE": PRINT
210 FOR
X =
I
TO 100
220 PRINT
X5
225 A$ = IIMKEY*: IF
A$
=
"@"
THEN END
230 NEXT
X
240 '
250
'
******* JUMP
TO
WHITE-OUT SUBROUTINE *******
2S0 '
270
X =
USR1 (0)
280 FOR
X
-
1
TO 1000:
NEXT
X
'DELAY LOOP
290 GOTO 200
300
'
310
'
******* DATA
IS
DECIMAL CODE
FOR HEX PROGRAM
*******
320 '
330 DATA
33>0>6B*54»19i
#
17
1
1
*G0>1 *255
t3
*237
»
17G ,201
Run
the
program.
An
equivalent
basic white
out routine takes a long
time by
comparison!
115