add option to enforce address field checksum verification in built-in RWTS

src/id/trace33.a

@@ -15,6 +15,7 @@ TraceDOS33
          sta   gTrack
          lda   #$09
          sta   gSector
+         jsr   IgnoreAddressChecksum
 precheck
          jsr   ReadSector
          bcc   +

src/passport.a

@@ -290,6 +290,7 @@ Action
          sta   TEXTTOP
          lda   #s_reading
          jsr   PrintByID
+         jsr   IgnoreAddressChecksum
          jsr   ReadSector
          bcc   +
          lda   #s_fail
@@ -508,6 +509,10 @@ StartWithUniv
 ; note: execution falls through here
 
 CopyUniversal
+         lda   #>EnforceAddressChecksum-1
+         pha
+         lda   #<EnforceAddressChecksum-1
+         pha
          lda   #$B8
 CopyUniversalAnywhere
          sta   dst+1

src/rwts.a

@@ -104,6 +104,14 @@ PreReadSector
 .exit    rts
 }
 
+IgnoreAddressChecksum
+         lda   #$00
+         !byte $2C        ; hide next LDA
+EnforceAddressChecksum
+         lda   #$B7
+         sta   $B98A
+         rts
+
 gTrack   !byte $00
 gSector  !byte $00
 

src/strings/en.a

@@ -234,7 +234,7 @@ StringTable
 ; can be set directly before calling PrintByID.
 ;
 .header
-         !text "Passport by 4am               2017-10-26",$00
+         !text "Passport by 4am               2017-10-29",$00
 .mainmenu
          !text "________________________________________",$8D,$8D,$8D,$8D,$8D,$8D,$8D
          !text "              "