passport/src/cffa.a

!zone {
EnterCFFAIfAvailable
         ldy   #$04
-        lda   $C7F6, y
         cmp   CFFASignature, y
         sec
         bne   +
         dey
         bpl   -
         jsr   $C730
         clc
+
         rts
CFFASignature
         !byte $43,$46,$33,$4B,$31
}