Adaptive built-in RWTS accepts any epilogue once, then enforces it

src/id/prodos.a

@@ -26,20 +26,3 @@ IDProDOS
          !byte $4C        ; JMP
          rts
 }
-
-!zone {
-PatchUniversalRWTSForOrigin
-         ldy   #$0F
--        lda   .a, y
-         sta   $b990, y
-         dey
-         bpl   -
-         ldy   #$14
--        lda   .b, y
-         sta   $b92f, y
-         dey
-         bpl   -
-         rts
-.a       !byte $C9,$AB,$D0,$0A,$EA,$BD,$8C,$C0,$C9,$AB,$F0,$95,$D0,$00,$18,$60
-.b       !byte $18,$60,$38,$A5,$2D,$E9,$11,$85,$2D,$18,$60,$00,$00,$00,$00,$00,$00,$00,$00,$38,$60
-}

src/passport.a

@@ -322,18 +322,39 @@ UseUniversal
          jsr   IncProgress
          jsr   StartWithUniv
          lda   gIsDinkeyDOS
-         bne   ReadWithRWTS
-; On disks with a ProDOS bootloader, we patch the universal RWTS in memory
-; so it can also read protected Origin disks like Ultima V and Times of Lore.
+         bne   +
+;
+; On Dinkey-DOS disks (e.g. Ultima V, Times of Lore), we start with the
+; universal RWTS then apply a patch in memory.
 ; These disks use a hybrid RWTS that alters the sector number in the
 ; address field based on the address epilogue. Once we normalize the
 ; sector numbers, no further patches are required, since the RWTS can also
 ; read unprotected disks. A separate patcher finds the actual code that
 ; alters the sector number to print it to the log.
+;
          jsr   PatchUniversalRWTSForOrigin
-
+         bmi   ReadWithRWTS          ; always branches
+;
+; On other disks that use the universal RWTS for the entire disk, we use
+; an adaptive RWTS that accepts any epilogue on the first sector but then
+; enforces all other sectors to have the same epilogue.
+;
++        jsr   PatchUniversalRWTSForAdaptive
+;
+; Some disks have different epilogues on track 0, so we stop using the
+; adaptive RWTS so we don't falsely accuse those disks of being damaged.
+;
+         lda   #kSectorResetAdaptiveRWTS
+         sta   T00S0F
+;
+; Some disks have an intentionally invalid checksum on T00,S00 (read by
+; the drive firmware, which doesn't verify it).
+;
+         lda   #kSectorIgnoreAddressChecksum
+         sta   T00S00
+;
 ; note: execution falls through here
-
+;
 ReadWithRWTS
          lda   #$22
          jsr   ChangeTrackNW
@@ -355,6 +376,10 @@ checksector
          cmp   #kSectorCustomLast
          bcs   +
          jsr   PreReadSector
+         tax
+         pla
+         txa
+         pha                                    ; replace status (on stack) with new status returned from PreReadSector
 +        cmp   #kSectorIgnore                   ; skip this sector?
          beq   nextsector
 +        cmp   #kSectorSwitchToBuiltinRWTS      ; switch to built-in RWTS before reading this sector?

src/rwts.a

@@ -86,8 +86,20 @@ endprotread
 ;-------------------------------
 PreReadSector
 !zone {
+         cmp   #kSectorResetAdaptiveRWTS
+         beq   .reset
+         cmp   #kSectorIgnoreAddressChecksum
+         beq   .ignore
          cmp   #kSectorCustomDOS32B4BB
-         bne   +
+         beq   .b4bb
+         rts
+.reset
+         jsr   CopyUniversal
+         lda   #kSectorRequired
+         rts
+.ignore
+         jmp   IgnoreAddressChecksum
+.b4bb
          ldx   jCallRWTS+2
          dex
          dex
@@ -99,15 +111,75 @@ PreReadSector
 .a       stx   $FF76
          ldx   #$ED
 .b       stx   $FFB2
-         bne   .exit      ; always branches
-+
 .exit    rts
 }
 
+!zone {
 IgnoreAddressChecksum
-         lda   #$00
-         sta   $B98A
+; out: A,Y preserved
+;      X clobbered
+         ldx   #$00
+         stx   $B98A
          rts
+}
+
+!zone {
+PatchUniversalRWTSForAdaptive
+; out:    N flag set
+         ldy   #$09
+-        lda   .addressepilogue, y
+         sta   $B994, y
+         lda   .dataepilogue, y
+         sta   $B938, y
+         dey
+         bpl   -
+         rts
+.addressepilogue          ; to $B994
+         !byte $8D,$91,$B9
+         !byte $A9,$AE
+         !byte $8D,$93,$B9
+         !byte $D0,$00
+.dataepilogue             ; to $B938
+         !byte $8D,$35,$B9
+         !byte $A9,$0A
+         !byte $8D,$37,$B9
+         !byte $18
+         !byte $60
+}
+
+!zone {
+PatchUniversalRWTSForOrigin
+; out:    N flag set
+         ldy   #$0F
+-        lda   .addressepilogue, y
+         sta   $B990, y
+         dey
+         bpl   -
+         ldy   #$0A
+-        lda   .dataepilogue, y
+         sta   $B92F, y
+         dey
+         bpl   -
+         rts
+.addressepilogue          ; to $B990
+         !byte $C9,$AB
+         !byte $D0,$0A
+         !byte $EA
+         !byte $BD,$8C,$C0
+         !byte $C9,$AB
+         !byte $F0,$95
+         !byte $D0,$00
+         !byte $18,$60
+.dataepilogue             ; to $B92F
+         !byte $18
+         !byte $60
+         !byte $38
+         !byte $A5,$2D
+         !byte $E9,$11
+         !byte $85,$2D
+         !byte $18
+         !byte $60
+}
 
 gTrack   !byte $00
 gSector  !byte $00

src/sectormap.a

@@ -31,7 +31,9 @@ kSectorRequired = $FF                ; sector is required (errors are fatal)
 kSectorCustomFirst = $C0
 kSectorCustomLast = $D0
 ; specific codes
-kSectorCustomDOS32B4BB = $C0            ; DOS 3.2 / JMP B4BB RWTS swapper
+kSectorResetAdaptiveRWTS = $C0       ; will accept any epilogue on next sector, then remember it
+kSectorIgnoreAddressChecksum = $C1   ; will ignore address field checksum
+kSectorCustomDOS32B4BB = $C2         ; DOS 3.2 / JMP B4BB RWTS swapper
 ;-------------------------------
 InitSectorMap
 !zone {

src/strings/en.a

@@ -137,7 +137,7 @@ StringTable
 ; can be set directly before calling PrintByID.
 ;
 .header
-         !text "Passport by 4am               2017-12-06",$00
+         !text "Passport by 4am               2017-12-11",$00
 .mainmenu
          !text "________________________________________",$8D,$8D,$8D,$8D,$8D,$8D,$8D
          !text "              "