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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 wrote:
Take rooms 'Master Bedroom' 'The nightmare room' and 'Top Landing'.
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'.
Changing exits can be done with a patch vector. You've probably
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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