Commodore Plus 4 - Page 332

320 Machine Language on the Commodore Plus/4
200E
200F
2010
2012
2013
2015
2017
2019
201B
201D
201F
2021
2023
2025
2027
2029
202B
202C
202E
2030
2032
2034
2036
2038
2039
203B
203D
203E
2040
2042
2044
2045
2047
2048
204A
204B
204D
204F
2051
2053
2055
2057
2059
205B
205C
205E
2060
0A
0A
26
0A
26
85
A5
C9
B0
65
85
90
E6
A5
C9
B0
38
E5
30
85
A5
C9
B0
38
E5
30
AA
A5
A4
91
88
10
CA
30
18
A5
69
85
90
E6
B0
A9
85
60
A9
85
60
DF
DF
DE
D8
28
3F
DE
DE
02
DF
DA
28
31
D8
2C
DD
DB
19
24
D9
IF
DC
CO
DE
FB
0D
DE
28
DE
EB
DF
E7
00
DD
FF
DD
ASL
ASL
ROL
ASL
ROL
STA
LDA
CMP
BCS
ADC
STA
BCC
INC
LDA
CMP
BCS
SEC
SBC
BMI
STA
LDA
CMP
BCS
SEC
SBC
BMI
TAX
LDA
LDY
STA
DEY
BPL
DEX
BMI
CLC
LDA
ADC
STA
BCC
INC
BCS
LDA
STA
RTS
LDA
STA
RTS
$DF
$DF
$DE
$D8
#$28
$205C
$DE
$DE
$2025
$DF
$DA
#$28
$205C
$D8
$205C
$DD
$DB
#$19
$205C
$D9
$205C
$DC
$DD
($DE),Y
$2042
$2057
$DE
#$28
$DE
$203E
$DF
$203E
#$00
$DD
#$FF
$DD
Multiply by two.
Multiply by two.
Double precision is now required.
Multiply by two low byte.
Multiply by two high byte.
Store low byte of screen pointer.
Get upper left corner x-coordinate.
Compare to maximum x value (plus one) •
If greater than, or equal to, return with
error.
Add to low byte of screen pointer.
Store low byte of screen pointer.
If no carry, go on.
Increment high byte of screen pointer.
Get lower right corner x-coordinate.
Compare to maximum x value (plus one) •
If greater than, or equal to, return with
error.
Prepare to subtract.
Subtract upper left x-coordinate.
If result is negative, return with error.
Number of columns is in $DD.
Get lower right corner y-coordinate.
Compare to maximum y value (plus one).
If greater than, or equal to, return with
error.
Prepare to subtract.
Subtract upper left y-coordinate.
If result is negative, return with error.
Number of lines is in .X.
Get fill character.
Set .Y to number of columns.
Store fill character on screen.
Decrement column count.
If not done, go back.
Decrement line count.
If finished, go to success return.
Prepare to add.
Get low byte of screen pointer.
Add one line.
Store in low byte of screen pointer.
If carry clear, go back to continue.
Increment high byte of screen pointer.
This is always taken.
Get ready for success return.
Store zero in return status location.
Return to BASIC program.
Get ready for error retarn.
Store $FF in return status location.
Return to BASIC program.