Changes to the JSW48 game engine to allow exit from intro screen
      ----------------------------------------------------------------
                         J.G.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:
8401                           8401 31 00 5C  LD  SP,&5C00  ; Initial stack
8404                           8404 C3 CA 87  JP  &87CA     ; Jump to start

8407                           8407 3E 7F     LD  A,&7F     ; keys 'b'-'spc'
8409                           8409 DB FE     IN  A,(&FE)
840B                           840B E6 03     AND 3         ; SS-SPC pressed?
840D                           840D C2 C9 96  JP  NZ,&96C9  ; no, check Enter
8410                           8410 11 FF 7F  LD  DE,&7FFF  ; top of memory
8413                           8413 C3 05 00  JP  &0005     ; jump to NEW_ETC

8416                           8416 00 00 00  spare
8419                           8419 00 00 00
841C                           841C 00 00 00
841F                           841F 00

88E3 01 FE AF  LD   BC,&AFFE   88E3 CD 07 84  CALL &8407    ; 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 07 84  CALL &8407    ; check keypress

This can be applied with the following hex patch file:

:1584010031005CC3CA873E7FDBFEE603C2C99611FF7FC30500CE
:0988E300CD078400000000000034
:0396C200CD07844D
:0000000000