Resource centre for ZX Spectrum games
using Manic Miner and Jet Set Willy game engines
Archive of the
Manic Miner & Jet Set Willy Yahoo! Group
messages
|
|
|
|
|
Message: 5813
Author: andrewbroad
Date: 22/04/2006
Subject: Re: The JSW64 memory-map
john_elliott_uk wrote:
>Not that the Sprites-screen lets you edit them! :-( I'll just mark
>> I decided to patch out the custom font in JSW64, and have it use
>> the standard Spectrum font (as in 48K MM/JSW). This makes 0:#C000-
>> C3FF free - unfortunately JSWED cannot detect this, and the
>> Memory-screen does not allow you to mark them as Free.
>
> It is possible to get round this by editing the memory map
> manually. The bytes controlling #C000-#C3FF are at #8668-#866B;
> change them to #60, for example, and the space becomes available
> for sprites.
#C100-C3FF as Free for now (#8669: 00 00 00).
What are the data at 0:#C000-C0FF? I thought they might be special
characters for ASCII codes 0-31, but when I used the hex-editor to
set a room's title to 00 01 02 ... 1F, they appeared as gobbledegook
in the game, and as Greek letters in JSWED (which is not WYSIWYG
when it comes to displaying ASCII-codes outside 32-127).
I can answer my own question now I remember that JSW128 uses 0:#C000-
C0FF to store the 8-bit room-number of each item. The 128-room
variants of JSW64 {V,W} also need to do this, while the 64-room
variants {X,Y,Z,[} only need to store 6-bit room-numbers in the
regular item-table.
So 0:#C000-C0FF are Free in Variants X,Y,Z,[, and could be used to
store user-defined graphics for ASCII codes 0-31.
--
Dr. Andrew Broad
http://geocities.com/andrewbroad/
http://geocities.com/andrewbroad/spectrum/
http://geocities.com/andrewbroad/spectrum/willy/
|
|
|