Resource centre for ZX Spectrum games
using Manic Miner and Jet Set Willy game engines
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Manic Miner & Jet Set Willy Yahoo! Group
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Message: 5326
Author: andrewbroad
Date: 18/12/2005
Subject: Harmless Fire-cells, and an amazing POKE for MM
I wish JSW64 had harmless Fire as a built-in cell-type.
A harmless Fire-cell behaves like an Air-cell, except that if it's
horizontally adjacent to a stand-onable cell, and you stand on both
cells together, you fall through as though they were both Air-cells -
which opens the door to a new field of quirky features! :-)
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Jet Set Willy
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POKE 38451,201 makes all Fire-cells in a JSW game harmless.
38447: LD A,(80BBh) ; get colour-attribute of current room's Fire
38450: CP (HL) ;;;;;; compare it with colour-attr. of current cell
38451: JP Z,37046 ;;; if equal then lose a life
38454: RET ;;;;;;;;;; else return
POKE 38451,201 knocks out the jump-instruction by overwriting it
with a RET instruction.
In JSW64, one could always have a patch-vector apply this poke on a
room-by-room basis - but it would be even better to be able to mix
harmful and harmless Fire-cells in the same room.
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Manic Miner
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The good news is that Manic Miner requires ONE POKE to be able to
mix harmful and harmless Fire-cells! :-)
(Bug-Byte edition)
37488: LD A,(804Dh) ; get colour-attribute of current room's Fire 1
37491: CP (HL) ;;;;;; compare it with colour-attr. of current cell
37492: JP Z,36101 ;;; if equal then lose a life
37495: LD A,(8056h) ; get colour-attribute of current room's Fire 2
37498: CP (HL) ;;;;;; compare it with colour-attr. of current cell
37499: JP Z,36101 ;;; if equal then lose a life
37502: RET ;;;;;;;;;; else return
POKE 37492,201 makes all Fire-cells in a MM game harmless (by
overwriting the first JP instruction with a RET - thus Fire-2 cells
aren't even considered).
POKE 37499,201 makes Fire-2 cells harmless, while Fire-1 cells
remain harmful! UNLIMITED POWER!!!
I've never studied a disassembly of JSW64, but given the way it
decouples cell-classes from cell-types, I'd be amazed if it were
that simple to mix harmful and harmless Fire-cells in the same room.
--
Dr. Andrew Broad
http://www.geocities.com/andrewbroad/
http://www.geocities.com/andrewbroad/spectrum/
http://www.geocities.com/andrewbroad/spectrum/willy/
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