2019-03-10 17:11:01 +00:00
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; SpiraDisc tracer
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2019-03-10 02:30:04 +00:00
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; written by qkumba
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;
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2019-03-10 17:11:01 +00:00
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; tested on
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; - Frogger
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; - Jawbreaker ][
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; - Lunar Leepers
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; - Pest Patrol
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;
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2019-03-10 02:30:04 +00:00
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IDSpiraDisc
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lda #8
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ldx #1
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ldy #12
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2019-03-10 03:29:19 +00:00
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jsr CompareMemory
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2019-03-10 02:30:04 +00:00
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!byte $86,$0A ;STA $0A
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!byte $8E,WILDCARD,WILDCARD ;STA $xxxx
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!byte $8E,WILDCARD,WILDCARD ;STA $xxxx
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!byte $90,$78 ;BCC *+$7A
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!byte $D0,$01 ;BNE *+$03
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bcs @exit
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; patch code to regain control after it loads sectors into $B500+
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lda #<@callback1
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sta $0870
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lda #>@callback1
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sta $0871
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@exit
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rts
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@callback1
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2019-04-11 02:47:54 +00:00
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lda $85FF
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beq @skip2
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lda $B5F9
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cmp #$8A
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bne +
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inc $B5F9
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+ lda $B608
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cmp #$8A
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bne +
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inc $B608
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+ lda $B618
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cmp #$8A
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bne +
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inc $B618
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+
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@skip2
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2019-03-10 02:30:04 +00:00
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; disable ROM checksum-failure branching
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2019-03-12 16:02:46 +00:00
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lda $B845
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cmp #$5C
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bne +
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2019-03-10 02:30:04 +00:00
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lda #0
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sta $B845
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2019-03-12 16:02:46 +00:00
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; and boot PROM checksum-failure branching
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sta $B606
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lda #$24
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sta $B60A
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2019-03-13 02:05:13 +00:00
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; and slot checksum-failure branching
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lda #$FD
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sta $BF41
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2019-03-13 16:57:49 +00:00
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; and slot scanning entirely
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lda #$D0
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sta $B899
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2019-03-12 16:02:46 +00:00
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+ jmp $B800
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