Jet Set Willy: Miscellaneous Patches

This page contains various pointless and/or amusing tweaks which can be applied to the Jet Set Willy engine. Some of them are available to be automatically applied by JSWED.

How to apply the patches

Download and unpack it. If necessary, compile hexpat.c. Then to apply a patch, use a command like this:

   hexpat -sna oldsnapshot newsnapshot hexfile


   hexpat -tap oldtap newtap hexfile

For example, to apply the Mono patch to a .SNA file, use:

   hexpat -sna jsw.sna jswmono.sna mono.hex

The patches

Wibble (more formally, Jet Set Wibble) makes the game engine display upside down.

Mono makes the game display in black and white, like the Dragon 32 version.

Wobble is a companion to Mono. It makes takeable items wobble to stand out (since with the Mono patch they no longer flash in colour). Again, this is similar to the Dragon 32 version.

Jiggle is similar, but makes items move up and down rather than left and right.

In both these patches, the speed at which the objects wobble can be changed by altering the byte at 0x97C7 (38856). Its current value is 1 (maximum speed); but it can be set to 2, 4, 8, ... for half-speed, quarter speed, eighth-speed, etc.

AdjRope is an attempt to patch the JSW engine so that ropes don't corrupt the guardian after them in the list. This is a more sophisticated version of the 'Adjacent Ropes' patch in JSWED.

This patch is to correct a problem with Mark Woodmass's "marginally faster" JSW. The original version suffered from the problem that the acceleration code overwrote the 'rope coordinates' table, so ropes displayed as a cloud of random dots. This creates a new rope coordinates table at 9F00h.

This patch displays the current room number in the bottom right-hand corner of the screen, as suggested by Andrew Broad.