Resource centre for ZX Spectrum games
using Manic Miner and Jet Set Willy game engines
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Message: 42
Author: andrewbroad
Date: 14/02/2000
Subject: Re: I need some technical help.
I don't use a PC for Spectrum emulation, but I'll tell you my own unorthodox and
extremely effective solution to this problem - other people could probably suggest
alternatives.
1. I would save the last 32768 bytes of the SNA file (i.e. addresses 32768-65535) as a
raw binary file.
2. I would reset the emulated Spectrum, type CLEAR 32767, and save
an SNA file at that point.
3. I would replace the last 32768 bytes of the SNA file
from Step 2 with the 32768-byte binary file from Step 1. This would give me the JSW game as
an SNA file saved from BASIC, ready to play by typing RANDOMIZE USR 33792 or
whatever.
Obviously a header program could be written at Step 2 before saving the SNA file, as I did for
Manic Miner 4. I actually created the original SNA file for MM4 using the above method,
except that I developed it on a real Spectrum rather than an emulator, and typed in the
32768-byte binary file rather than saving it from an existing SNA file. Lee Tonks subsequently
converted MM4 into a TAP file for me, which is a more desirable format for releasing games than
an SNA file.
I have written a Java program called SPECSAISIE which I use to
manipulate SNA and TAP files, although some of the functionality is probably replicated by the PC
Spectrum emulators.
SPECSAISIE enables me to convert TAP files to raw binaries (by
stripping off the headers), and to 'sew' raw binaries onto existing TAP files - for example, you
could sew an SCR file (a raw 6912-byte representation of a screenshot) onto a SCREEN$ file
in a TAP file, as I did for the We Pretty loading screen.
SPECSAISIE doesn't
currently support saving raw binaries from SNA files and sewing raw binaries onto SNA files, but
it wouldn't be very difficult to adapt it to do so.
SPECSAISIE will also be able
to create TAP files from SNA files, but unfortunately that hasn't been implemented yet
because it's very difficult and I'm very busy. But I think some PC Spectrum emulators would
let you save TAP files, although it might be necessary to 'purify' the SNA file using the
three-step method above. Then again, JetSet Edit should allow you to save a TAP file on a good
enough emulator (my emulator, MacSpectacle, doesn't let you save TAP files).
If anyone
really wants SPECSAISIE as it stands, I will consider releasing it, even in its current
incomplete state.
--
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/download/ target=new>http://www.cs.man.ac.uk/~broada/spectrum/download/>
http://www.cs.man.ac.uk/~broada/spectrum/download/specsaisie.html target=new>http://www.cs.man.ac.uk/~broada/spectrum/download/specsaisie.html>
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