;-------------------------------
; #THUNDER
; boot1 jumps to $B3C1 to change RWTS,
; epilogue checker jumps to $B6B3 to
; check timing bits, late DOS routes
; through nibble check at $B74B
; e.g. Thunder Mountain versions of
; Dig Dug, Pac-Man, Galaxian
;-------------------------------
_thunder
         lda   gIsBoot0   ; if DOS 3.3 boot0 loader
         bne   thunder_no
         lda   gIsBoot1   ; and DOS 3.3 boot1 loader
         bne   thunder_no
         lda   #$03
         ldx   #$3E
         ldy   #$04
         jsr   compare    ; and T00,S03,$3E ==
         !byte $4C,$B3,$B6,$EA
         bcc   +
thunder_no
         jmp   thunder_exit
+
         lda   #$01
         ldx   #$47
         ldy   #$4C
         jsr   compare    ; and T00,S01,$47 ==
         !byte $4C
         !byte $C1,$B3,$60,$48,$A9,02,$8D,$EC
         !byte $B7,$A9,00,$8D,$EB,$B7,$8D,$F2
         !byte $B7,$A9,05,$8D,$ED,$B7,$A9,$36
         !byte $8D,$F0,$B7,$A9,$B4,$8D,$F1,$B7
         !byte $A9,01,$8D,$E1,$B7,$8D,$F4,$B7
         !byte $20,$93,$B7,$90,09,$4C,$62,$FA
         !byte $EA,$EA,$EA,$EA,$EA,$EA,$20,$36
         !byte $B4,$68,$F0,03,$6C,$72,$AA,$6C
         !byte $58,$9D,00,$A9,00,$F0,$BC,$A9
         !byte 01,$D0,$B8
         bcs   thunder_exit
         lda   #s_thunder
         jsr   PrintByID
         lda   #$01
         ldx   #$48
         ldy   #$02
         jsr   modify     ; then set T00,S01,$48 =
         !byte $1F,$B4
         lda   #$01
         ldx   #$7E
         ldy   #$01
         jsr   modify     ; and set T00,S01,$7E =
         !byte $2C
         lda   #$03
         ldx   #$3E
         ldy   #$04
         jsr   modify     ; and set T00,S03,$3E =
         !byte $C9,$AA,$F0,$5C
thunder_exit