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General Zoff
Account closed
Registered: Dec 2004
Posts: 7 |
Stupid Routines ....
Found this one on one of my old work disks ...
Let's collect the most stupid routines you have written on your old C64 ... ;-)
.C:6000 78 SEI
.C:6001 A2 00 LDX #$00
.C:6003 BD 11 60 LDA $6011,X
.C:6006 9D 00 00 STA $0000,X
.C:6009 E8 INX
.C:600a E0 40 CPX #$40
.C:600c D0 F5 BNE $6003
.C:600e 4C 00 00 JMP $0000
.C:6011 2F 34 A9 RLA $A934
.C:6014 A9 EA LDA #$EA
.C:6016 8D 34 A9 STA $A934
.C:6019 F0 24 BEQ $603F
.C:601b A2 00 LDX #$00
.C:601d A9 EA LDA #$EA
.C:601f 9D 40 00 STA $0040,X
.C:6022 E8 INX
.C:6023 D0 F8 BNE $601D
.C:6025 EE 10 00 INC $0010
.C:6028 AD 10 00 LDA $0010
.C:602b C9 00 CMP #$00
.C:602d F0 0B BEQ $603A
.C:602f C9 FF CMP #$FF
.C:6031 D0 E8 BNE $601B
.C:6033 A9 00 LDA #$00
.C:6035 8D 0F 00 STA $000F
.C:6038 F0 E1 BEQ $601B
.C:603a A9 D0 LDA #$D0
.C:603c 8D 08 00 STA $0008
.C:603f A9 37 LDA #$37
.C:6041 85 01 STA $01
.C:6043 EE 20 D0 INC $D020
.C:6046 A9 34 LDA #$34
.C:6048 85 01 STA $01
.C:604a EA NOP
.C:604b EA NOP
.C:604c EA NOP
.C:604d EA NOP
.C:604e EA NOP
.C:604f EA NOP
.C:6050 EA NOP
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Soren
Registered: Dec 2001
Posts: 547 |
Loop: inc $D418
dec $D012
lda #$01
tay
dey
tya
clc
adc #$00
tax
inx
txa
lda #$01
sta $0801
jmp Loop
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j0x
Registered: Mar 2004
Posts: 215 |
Jeff: Obfuscated flatulence-sound code?
Zoff: The most memory-wasteful way of changing the border colour at 7.5 Hz?
Good (insane) fun :) |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Try this:
*=$1000
soundfx4
JSR fxloop
JMP soundfx4
fxloop
LDA #$0F
STA $D418 ; SID Filter mode/master volume.
LDX #$06
.re5 LDA data4,X
STA $D40E,X ; SID Voice 3 - frequency (LSB).
DEX
BPL .re5
LDA #$10
STA $D412 ; SID Envelope 3 - control register.
.re6 JSR subrout2
AND #$1F
CMP #$08
BCC .re6
STA $D40F ; SID Voice 3 - frequency (MSB).
LDA #$30
STA $D413 ; SID Envelope 3 - attack/decay levels.
LDA #$11
STA $D412 ; SID Envelope 3 - control register.
RTS
data4
!byte $32,$2f,$00,$00,$81,$19,$01
subrout2
LDA $DC04 ; CIA#1 Timer A (LSB).
EOR $DC05 ; CIA#1 Timer A (MSB).
EOR $DD04 ; CIA#2 Timer A (LSB).
ADC $DD05 ; CIA#2 Timer A (MSB).
EOR $DD06 ; CIA#2 Timer B (LSB).
EOR $DD07 ; CIA#2 Timer B (MSB).
RTS
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Scout
Registered: Dec 2002
Posts: 1570 |
*=$1000
sei
lda #$0b
sta $d011
ldy #$01
loop
ldx #$01
dex
bne *-1
nop
sty $d020
ldx #$01
dex
bne *-1
nop
stx $d020
jmp loop
---
8Bit Mayhem - The C64 Scenemusic Podcast
http://8bitmayhem.untergrund.net |
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Raf
Registered: Nov 2003
Posts: 343 |
* = $1000
jmp *
;-)
www.vulture.c64.org |
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j0x
Registered: Mar 2004
Posts: 215 |
Routine 1:
loop1 inc $d020
bne loop1
rts
Routine 2:
loop2 dec $d020
bne loop2
rts
Spot the not-so-obvious difference
[hint: no, it's not that the colour order is reversed]
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Mace
Registered: May 2002
Posts: 1799 |
j0x: the first runs longer than the second, as it takes longer from any value <#$10 to reach #$00 again when you increase then when you decrease. |
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j0x
Registered: Mar 2004
Posts: 215 |
Mace: Actually, Routine 2 runs longer.
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Oswald
Registered: Apr 2002
Posts: 5086 |
some c64s has random upper 4 bits... |
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algorithm
Registered: May 2002
Posts: 705 |
Or that routine 2 is never run |
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