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using Manic Miner and Jet Set Willy game engines
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Message: 124
Author: andrewbroad
Date: 16/05/2000
Subject: Re: neeeeeed some infoooooooo
> questions: is it okay to clear the lastthree
> screens (60-63 i think) and use those. they
look
> like machine code.
Yes - Rooms 61-63 in
the original JSW contain dead code (TRS-80 device
drivers, or something like that). It's safe to overwrite
these rooms, but...
One of the fixes for the
Pause Bug (to stop JSW crashing when you pause with
Interface I plugged in) corrupts Room 63,
namely:
35591: 195,240,255 (JP 65520)
65520: 197 (PUSH
BC)
65521: 33,0,154 (LD HL,39424)
65524: 17,0,90 (LD DE,
23040)
65527: 1,0,1 (LD BC,256)
65530: 237,176
(LDIR)
65532: 193 (POP BC)
65533: 195,18,139 (JP
35602)
If you use this Pause Bug fix, you can't edit Room
63 because addresses 65520-65535 happen to coincide
with the guardian instance list for Room 63. If you
start with the Pause Bug fix in, and then edit Room 63,
you will corrupt the above code, probably with the
consequence that it will crash when you pause it. If you put
the Pause Bug fix in after writing the game, you will
corrupt the guardians in Room 63. I've seen both these
problems in existing JSW games.
So my advice is to
leave the Pause Bug fix out (you don't need it anyway,
unless you're using Interface I), and if you find to
your horror that the Pause Bug fix (i.e. the above
code) is in your JSW game, you can remove it using POKE
35591,33: POKE 35592,0: POKE 35593,154 (which replaces the
JP 65520 instruction with the original LD HL,39424
instruction, thus unbinding the Room 63 guardian instance
list).
By the way, there is another fix for the Pause Bug,
which doesn't corrupt Room 63, namely POKE 35537,62:
POKE 35539,219: POKE 35540,254: POKE 35615,62: POKE
35620,219: POKE 35621,254.
> secondly, and
more importantly, how do you go
> about getting
a finishable game? i've heard that
> jsw is
impossible to complete, is this true?
The original
JSW is impossible to complete for the following four
reasons, each of which Software Projects issued an
official poke to fix:
1. There's a faulty arrow in
"The Attic", which corrupts guardians in other rooms
such as "The Chapel", "The Kitchen" and "We must
perform a quirkafleeg". This is the infamous Attic Bug,
and POKE 59901,82 fixes it.
2. There's an
invisible and unreachable item by the Cross in "First
Landing". POKE 42138,11 moves it to "The Hall", where it is
still invisible but can be collected by walking along
the roof of the hall.
3. There's a wall block
in "The Banyan Tree" which prevents you climbing up
the right-hand side of the tree. POKE 56876,4
replaces it with a floor block.
4. It's impossible
to collect the rightmost item in "Conservatory Roof"
because there's a static nasty in the way (not to mention
you have to climb up the right of the Banyan tree to
get here). POKE 60231,0 removes that static nasty,
although you still have to sacrifice a life to collect one
of the other items :-(
> when you collect
all the objects does the
> 'maria' sprite
(which i intend to change) let
> you
pass?
Maria disappears when you collect all the items,
allowing you to get to the bed.
> and does the
pillow (bad) block kill you, or
> does it take you
to an ending sequence?
It would kill you, but
as soon as you walk into the bed (conveyor), the
ending sequence is triggered.
--
Andrew
Broad
broada@...
http://www.cs.man.ac.uk/~broada/ target=new>http://www.cs.man.ac.uk/~broada/>
http://www.cs.man.ac.uk/~broada/spectrum/ target=new>http://www.cs.man.ac.uk/~broada/spectrum/>
http://www.cs.man.ac.uk/~broada/spectrum/willy/ target=new>http://www.cs.man.ac.uk/~broada/spectrum/willy/>
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