Commodore Plus 4 - Page 314

302 Machine Language on the Commodore Plus/4
. 2026 8D 0A FF STA $FF0A
2029
202B
202D
2030
2033
2034
2036
2037
203A
203C
203F
2042
2045
2047
2049
A2
A9
9D
9D
CA
10
58
20
F0
20
4C
AD
29
F0
A9
02
30
00
25
F7
E4
FB
D2
37
09
40
23
00
0C
0C
FF
FF
20
FF
LDX
LDA
STA
STA
DEX
BPL
CLI
JSR
BEQ
JSR
JMP
LDA
AND
BEQ
LDA
#$02
#$30
$0C00,X
$0C25,X
$202D
$FFE4
$2037
$FFD2
$2037
$FF09
#$40
$206C
#$00
. 204B 8D 04 FF STA $FF04
. 204E A9 80 LDA #$80
. 2050 8D 05 FF STA $FF05
. 2053 A9 40 LDA #$40
. 2055 8D 09 FF STA $FF09
. 2058 A2 02 LDX #$02
. 205A FE 00 0C INC $0C00rX
. 205D BD 00 0C LDA $0C00,X
. 2060 C9 3A CMP #$3A
2062
2064
2066
2069
206A
206C
206F
2071
2073
90
A9
9D
CA
10
AD
29
F0
A9
08
30
00
EE
09
10
23
00
BOC
LDA
0C STA
DEX
BPL
FF LDA
AND
BEQ
LDA
$206C
#$30
$0C00,X
$205A
$FF09
#$10
$2096
#$00
. 2075 8D 02 FF STA $FF02
. 2078 A9 40 LDA #$40
. 207A 8D 03 FF STA $FF03
. 207D A9 10 LDA #$10
. 207F 8D 09 FF STA $FF09
. 2082 A2 02 LDX #$02
Interrupt enable timers two and three
and the raster interrupts used by the
operating system•
.X indexes the counters on the screen,
.A contains the screen code for a zero.
Store zeroes to left counter.
Store zeroes to right counter.
Next counter location.
If not done, go back.
Start the interrupts going.
Get a character from keyboard queue.
If none, look again.
Put character to screen.
Look at keyboard queue again.
Interrupt service. Get interrupt status
register.
Mask off all but timer three bit.
If not a timer three interrupt, go on.
Get low byte of start value for timer
three.
Store in start value register; stop timer
three.
Get high byte of start value for timer
three.
Store in start value register; start
timer three.
Get value with bit 6 set to 1.
Clear interrupt status bit for timer
three.
.X indexes the counter on the screen.
Increment left counter location.
Load value.
Compare to one more than screen code for
nine.
If valid number code, go on.
Get screen code for zero.
Store in counter location.
Go on to next location.
If more digits, go back.
Get interrupt status register.
Mask off all but timer two bit.
If not a timer two interrupt, go on.
Get low byte of start value for timer
two.
Store in start value register; stop timer
two.
Get high byte of start value for timer
two.
Store in start value register; start
timer two.
Get value with bit 4 set to 1.
Clear interrupt status bit for timer two.
.X indexes the counter on the screen.