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https://github.com/a2-4am/passport.git
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improve detection of unformatted tracks and nibble count tracks (fixes Thunderbombs, Hi-Res Football, and many others)
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4am
parent
1b9a1c847e
commit
9d9146382b
191
src/analyze.a
191
src/analyze.a
@ -6,55 +6,37 @@
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!zone {
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SkipTrack
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;
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; 1) $EEEF protection track (EEEFBBBAFAAE nibble sequence)
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; [must come first because track would otherwise pass the IsUnformatted test below]
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; [speed optimization: only check on track $22]
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; Electronic Arts protection track?
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;
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.checkeeef
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lda gTrack
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cmp #$22
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bne .checkunformat
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jsr IsEEEF
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bcs .checkunformat
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lda #s_eeef
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bcc .skiptrack ; always taken
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jsr IsEATrack6
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lda #s_eatrk6
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bcc .print
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;
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; 2) unformatted track
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; Unformatted track?
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;
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.checkunformat
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jsr IsUnformatted
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bcs .checkf7f6
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+ lda #s_unformat
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bcc .skiptrack ; always taken
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bcs +
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;
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; 3) $F7F6 protection track (F7F6EFEAAB nibble sequence)
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; $F7F6EFEAAB protection track?
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; (initially presents as unformatted, needs separate test because it
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; triggers special handling)
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;
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.checkf7f6
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jsr IsF7F6
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bcs .checksync
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lda #s_unformat
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bcs .print
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lda #s_f7
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bit gMode
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bpl .checksync
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bvc .checksync
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bpl .print
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bvc .print
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; if we're in 'crack' mode, restart the scan to find the protection code
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jmp SetupF7F6SecondRound
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;
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; 4) nibble count track (mostly $FF sync bytes)
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; Nibble count track?
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;
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.checksync
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jsr IsSyncBytes
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bcs .checktrack6
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+ jsr JustTheSameDamnThingOverAndOver
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bcs .donotskip
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lda #s_sync
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bcc .skiptrack ; always taken
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;
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; 5) track simply does not exist (Electronic Arts in particular)
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;
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.checktrack6
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jsr IsEATrack6
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bcs .fail
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lda #s_eatrk6
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; note: execution falls through here
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.skiptrack
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.print
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jsr PrintByID
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;
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; Skipping T22 on a ProDOS disk might indicate the presence of a
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@ -73,7 +55,7 @@ SkipTrack
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sta gPossibleGamco
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+ clc
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!byte $24 ; hides next SEC
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.fail
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.donotskip
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sec
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rts
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}
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@ -93,7 +75,7 @@ IsF7F6
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lda $C0E9
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lda #$00
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jsr WAIT
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lda #$20
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lda #$19
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sta nibcount
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ldy #$00
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- lda $C0EC
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@ -162,108 +144,87 @@ SetupF7F6SecondRound
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jmp RestartScan
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;-------------------------------
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; IsEEEF
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; check for a specific nibble sequence
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; ("EE EF BB BA FA AE") that is used by a
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; whole-track protection scheme
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; JustTheSameDamnThingOverAndOver
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; check if track has a large sequence of repeated bytes
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;
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; in slot 6, drive 1 is on track to test
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; out C clear if sequence was found
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; C set if sequence was not found
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; out C clear if found
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; C set otherwise
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;-------------------------------
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!zone {
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IsEEEF
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JustTheSameDamnThingOverAndOver
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lda $C0E9
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lda #$00
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jsr WAIT
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lda #$20
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sta nibcount
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ldy #$00
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- lda $C0EC
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bpl -
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cmp #$EE
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beq +
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.restart iny
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bne -
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dec nibcount
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bne -
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beq .fail
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+
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- lda $C0EC
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bpl -
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cmp #$EF
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bne .restart
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- lda $C0EC
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bpl -
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cmp #$BB
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bne .restart
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- lda $C0EC
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bpl -
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cmp #$BA
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bne .restart
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- lda $C0EC
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bpl -
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cmp #$FA
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bne .restart
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- lda $C0EC
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bpl -
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cmp #$AE
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bne .restart
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lda #$19
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sta unform+1
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ldx #$00
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;
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; Timing-sensitive code! Cycle counts in margin for worst case path
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;
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.reset ldy #$00 ; 2
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sta .cmp+1 ; 4
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.loop lda $C0EC
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bpl .loop ; 3 when not taken
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dex ; 2
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bne .cmp ; 3 when not taken
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dec unform+1 ; 5
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beq .notfound ; 3 when not taken
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.cmp cmp #$d1 ; 2
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bne .reset ; 3 when not taken
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iny ; 2
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bne .loop ; 2 when taken
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clc
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!byte $24 ; hides SEC
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.fail sec
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!byte $24
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.notfound
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sec
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lda $C0E8
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rts
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}
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;-------------------------------
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; IsSyncBytes
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; check if track is mostly $FF bytes
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;
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; in slot 6, drive 1 is on track to test
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; out C clear if track is mostly just $FF bytes
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; C set otherwise
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;-------------------------------
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IsSyncBytes
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lda #$FD
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sta gNIBTableFF
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jsr IsUnformatted
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lda #$3F
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sta gNIBTableFF
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rts
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;-------------------------------
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; IsUnformatted
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; check if track is unformatted
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; check if track is unformatted by counting
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; the number of valid nibbles in a row
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;
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; in slot 6, drive 1 is on track to test
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; out C clear if track is unformatted
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; C set if track is formatted
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;-------------------------------
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!zone {
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IsUnformatted
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lda #$FD
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sta gNIBTableFF
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lda $C0E9
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jsr WAIT
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lda #$00
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sta unform
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lda #$19
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sta unform+1
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jsr WAIT
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lda #$20
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sta nibcount
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ldy #$00
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nibloop ldx $C0EC
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bpl nibloop
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lda gNIBTable,x
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bpl +
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inc unform
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bne +
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inc unform+1
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+ iny
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bne nibloop
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dec nibcount
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bne nibloop
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;
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; Timing-sensitive code! Cycle counts in margin for worst case path
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;
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.reset ldy #$00
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.loop ldx $C0EC
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bpl .loop ; 3 when not taken
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dec unform ; 5
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bne + ; 3 when not taken
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dec unform+1 ; 5
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beq .unformatted;3 when not taken
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+ lda gNIBTable,x; 4
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bmi .reset ; 3 when not taken
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iny ; 2
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bne .loop ; 2 when taken
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sec
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!byte $24
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.unformatted
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clc
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lda $C0E8
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lda #$18
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cmp unform+1
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lda #$3F
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sta gNIBTableFF
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rts
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}
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;-------------------------------
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; xHeredityDog
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@ -137,7 +137,7 @@ StringTable
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; can be set directly before calling PrintByID.
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;
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.header
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!text "Passport by 4am 2017-12-26",$00
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!text "Passport by 4am 2017-12-27",$00
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.mainmenu
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!text "________________________________________",$8D,$8D,$8D,$8D,$8D,$8D,$8D
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!text " "
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@ -370,7 +370,7 @@ StringTable
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.eatrk6
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!text "T06 Found EA protection track",$8D,$00
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.eeef
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!text "T%t Found $EEEFBBBA protection track",$8D,$00
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!byte $00
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.poke
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!text "T%t,S%0 BASIC program POKEs protection",$8D
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!text "check into memory and CALLs it.",$8D,$00
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