Resource centre for ZX Spectrum games
using Manic Miner and Jet Set Willy game engines
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Message: 6235
Author: john_elliott_uk
Date: 29/08/2007
Subject: Re: Tweaking the JSW engine: One for the experts
--- In manicminerandjetsetwilly@yahoogroups.com, adban_de_corcy
> Take rooms 'Master Bedroom' 'The nightmare room' and 'Top Landing'.
Changing exits can be done with a patch vector. You've probably
>
> Now, when the time is divisible by 5 (it ends with 0 or 5), you get to
> 'Master Bedroom' if you go to the left of 'Top Landing'.
>
> Now, if the time is not divisible by five, then when you exit to the
> left of 'Top Landing' you enter 'The nightmare room'.
noticed that it happens in the original JSW64.
For a timed change of exits you'd use the 'main loop' patch vector,
something like this:
LD D,nnn ;Room number of the top landing
LD A,(time) ;Last digit of the clock
CP '0'
JR Z,doit
CP '5'
JR Z,doit
LD D,mmm ;Room number of the nightmare room
doit:
LD A,D
LD (80E9h),A ;Set exit to be the specified value.
RET
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