Changes to the JSW48 game engine to allow exit from intro screen
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                    Graham Harston, 15 March 1985

This allows you to exit from Jet Set Willy at the intro screen by pressing
SymbolShift-Space. It does a NEW with the top of memory set to &7FFF, so
keeping the JSW code intact.

Original code:                 Change to:
840C                           840C C9       RET           ; Jump to start

840D                           840D 3E 7F    LD  A,&7F     ; keys 'b'-'spc'
840F                           840F DB FE    IN  A,(&FE)
8411                           8411 E6 03    AND 3         ; SS-SPC pressed?
8413                           8413 C2 C9 96 JP  NZ,&96C9  ; no, check Enter
8416                           8416 11 FF 7F LD  DE,&7FFF  ; top of memory
8419                           8419 C3 05 00 JP  &0005     ; jump to NEW_ETC

841C                           841C spare
841D                           841D
841E                           841E
841F                           841F

88E3 01 FE AF   LD   BC,&AFFE  88E3 CD 0D 84 CALL &840D    ; check keypress
88E6 ED 78      IN   A,(C)     88E6 00 00    NOP:NOP
88E8 E6 01      AND  &01       88E8 00 00    NOP:NOP
88EA FE 01      CP   &01       88EA 00 00    NOP:NOP

96C2 CD C9 96   CALL &96C9     96C2 CD 0D 84 CALL &840D    ; check keypress