BBC Micro cassette Elite | BBC Micro disc Elite | Acorn Electron Elite | 6502 Second Processor Elite | Commodore 64 Elite | Apple II Elite | BBC Master Elite | NES Elite | Elite-A | Teletext Elite | Elite Universe Editor | Elite Compendium (BBC Master) | Elite Compendium (BBC Micro) | Elite over Econet | Flicker-free Commodore 64 Elite | BBC Micro Aviator | BBC Micro Revs | Archimedes Lander
This repository contains the original source code for Elite on the Commodore 64, with every single line documented and (for the most part) explained. It is literally the original source code, just heavily commented.
It is a companion to the elite.bbcelite.com website.
See the introduction for more information, or jump straight into the documented source code.
This repository contains the original source code for Elite on the Commodore 64, with every single line documented and (for the most part) explained.
You can build the fully functioning game from this source. Four variants are currently supported: the Firebird GMA85 NTSC variant, the Firebird GMA86 PAL variant, the variant built by the source disk build process, and the variant built from the binary files already on the source disk.
This repository is a companion to the elite.bbcelite.com website, which contains all the code from this repository, but laid out in a much more human-friendly fashion. The links at the top of this page will take you to repositories for the other versions of Elite that are covered by this project.
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If you want to browse the source and read about how Elite works under the hood, you will probably find the website a better place to start than this repository.
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If you would rather explore the source code in your favourite IDE, then the annotated source is what you're looking for. It contains the exact same content as the website, so you won't be missing out (the website is generated from the source files, so they are guaranteed to be identical). You might also like to read the section on browsing the source in an IDE for some tips.
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If you want to build Commodore 64 Elite from the source on a modern computer, to produce a working game disk that can be loaded into a Commodore 64 or an emulator, then you want the section on building Commodore 64 Elite from the source.
My hope is that this repository and the accompanying website will be useful for those who want to learn more about Elite and what makes it tick. It is provided on an educational and non-profit basis, with the aim of helping people appreciate one of the most iconic games of the 8-bit era.
Commodore 64 Elite was written by Ian Bell and David Braben and is copyright © D. Braben and I. Bell 1985.
The code on this site is identical to the source disks released on Ian Bell's personal website (it's just been reformatted to be more readable).
The commentary is copyright © Mark Moxon. Any misunderstandings or mistakes in the documentation are entirely my fault.
Huge thanks are due to the original authors for not only creating such an important piece of my childhood, but also for releasing the source code for us to play with. Also, a big thumbs up to Kroc Camen for his epic Elite Harmless project, which is a really useful reference for anyone exploring the Commodore 64 binaries. Finally, thanks to the gurus in this Lemon64 forum thread for their sage advice.
The following archive from Ian Bell's personal website forms the basis for this project:
This repository is not provided with a licence, and there is intentionally no LICENSE file provided.
According to GitHub's licensing documentation, this means that "the default copyright laws apply, meaning that you retain all rights to your source code and no one may reproduce, distribute, or create derivative works from your work".
The reason for this is that my commentary is intertwined with the original Elite source code, and the original source code is copyright. The whole site is therefore covered by default copyright law, to ensure that this copyright is respected.
Under GitHub's rules, you have the right to read and fork this repository... but that's it. No other use is permitted, I'm afraid.
My hope is that the educational and non-profit intentions of this repository will enable it to stay hosted and available, but the original copyright holders do have the right to ask for it to be taken down, in which case I will comply without hesitation. I do hope, though, that along with the various other disassemblies and commentaries of this source, it will remain viable.
If you want to browse the source in an IDE, you might find the following useful.
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The most interesting files are in the main-sources folder:
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The main game's source code is in the elite-source.asm and elite-data.asm files (containing the game code and game data respectively) - this is the motherlode and probably contains all the stuff you're interested in.
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The game's loader is in the elite-loader.asm file - this is mainly concerned with setup and copy protection.
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It's probably worth skimming through the notes on terminology and notations on the accompanying website, as this explains a number of terms used in the commentary, without which it might be a bit tricky to follow at times (in particular, you should understand the terminology I use for multi-byte numbers).
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The accompanying website contains a number of "deep dive" articles, each of which goes into an aspect of the game in detail. Routines that are explained further in these articles are tagged with the label
Deep dive:and the relevant article name. -
There are loads of routines and variables in Elite - literally hundreds. You can find them in the source files by searching for the following:
Type: Subroutine,Type: Variable,Type: WorkspaceandType: Macro. -
If you know the name of a routine, you can find it by searching for
Name: <name>, as inName: SCAN(for the 3D scanner routine) orName: LL9(for the ship-drawing routine). -
The entry point for the main game code is routine
BEGIN, which you can find by searching forName: BEGIN. If you want to follow the program flow all the way from the title screen around the main game loop, then you can find a number of deep dives on program flow on the accompanying website. -
The source code is designed to be read at an 80-column width and with a monospaced font, just like in the good old days.
I hope you enjoy exploring the inner workings of Commmodore 64 Elite as much as I have.
There are five main folders in this repository, which reflect the order of the build process.
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1-source-files contains all the different source files, such as the main assembler source files, image binaries, fonts, boot files and so on.
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2-build-files contains build-related scripts, such as the checksum, encryption and crc32 verification scripts.
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3-assembled-output contains the output from the assembly process, when the source files are assembled and the results processed by the build files.
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4-reference-binaries contains the correct binaries for each variant, so we can verify that our assembled output matches the reference.
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5-compiled-game-disks contains the final output of the build process: a d64 disk image that contains the compiled game and which can be run on real hardware or in an emulator.
Builds are supported for both Windows and Mac/Linux systems. In all cases the build process is defined in the Makefile provided.
You will need the following to build Commodore 64 Elite from the source:
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BeebAsm, which can be downloaded from the BeebAsm repository. Mac and Linux users will have to build their own executable with
make code, while Windows users can just download thebeebasm.exefile. -
Python. The build process has only been tested on 3.x, but 2.7 might work.
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c1541 from the VICE emulator, which can be downloaded from the VICE site.
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Mac and Linux users may need to install
makeif it isn't already present (for Windows users,make.exeis included in this repository).
You may be wondering why we're using BeebAsm - a BBC Micro assembler - to build the Commodore 64 version of Elite. This is because Commodore 64 Elite is a conversion of 6502 Second Processor Elite, which itself is a direct descendant of the original 1984 release for the BBC Micro and Acorn Electron (and the same is true of the Apple II and NES versions of Elite - they are all cut from the same cloth). The NES version aside, all of the 6502 versions of Elite were built and assembled on a BBC Micro, including the Commodore and Apple versions, so BeebAsm is a good modern assembler to use for the Commodore 64 version as well.
For details of how the build process works, see the build documentation on bbcelite.com.
Let's look at how to build Commodore 64 Elite from the source.
For Windows users, there is a batch file called make.bat which you can use to build the game. Before this will work, you should edit the batch file and change the values of the BEEBASM, PYTHON and C1451 variables to point to the locations of your beebasm.exe, python.exe and c1541.exe executables. You also need to change directory to the repository folder (i.e. the same folder as make.bat).
All being well, entering the following into a command window:
make.bat
will produce a file called elite-commodore-64-gma85-ntsc.d64 in the 5-compiled-game-disks folder that contains the Firebird GMA85 NTSC variant, which you can then load into an emulator, or into a real Commodore 64.
The build process uses a standard GNU Makefile, so you just need to install make if your system doesn't already have it. If BeebAsm, Python or c1541 are not on your path, then you can either fix this, or you can edit the Makefile and change the BEEBASM, PYTHON and C1451 variables in the first three lines to point to their locations. You also need to change directory to the repository folder (i.e. the same folder as Makefile).
All being well, entering the following into a terminal window:
make
will produce a file called elite-commodore-64-gma85-ntsc.d64 in the 5-compiled-game-disks folder that contains the Firebird GMA85 NTSC variant, which you can then load into an emulator, or into a real Commodore 64.
By default the build process will create a typical Elite game disk with a standard commander and verified binaries. There are various arguments you can pass to the build to change how it works. They are:
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variant=<name>- Build the specified variant:variant=gma85-ntsc(default)variant=gma86-palvariant=source-disk-buildvariant=source-disk-files
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commander=max- Start with a maxed-out commander (specifically, this is the test commander file from the original source, which is almost but not quite maxed-out) -
encrypt=no- Disable encryption and checksum routines -
match=no- Do not attempt to match the original game binaries (i.e. omit workspace noise) -
verify=no- Disable crc32 verification of the game binaries
So, for example:
make variant=gma86-pal commander=max encrypt=no match=no verify=no
will build an unencrypted GMA85 PAL variant with a maxed-out commander, no workspace noise and no crc32 verification.
The unencrypted version should be more useful for anyone who wants to make modifications to the game code. As this argument produces unencrypted files, the binaries produced will be quite different to the binaries on the original source disk, which are encrypted.
See below for more on the verification process.
If you change the source code in any way, you may break the game; if so, it will typically hang at the loading screen, though in some versions it may hang when launching from the space station.
To fix this, you may need to update some of the hard-coded addresses in the checksum script so that they match the new addresses in your changed version of the code. See the comments in the elite-checksum.py script for details.
The default build process prints out checksums of all the generated files, along with the checksums of the files from the original sources. You can disable verification by passing verify=no to the build.
The Python script crc32.py in the 2-build-files folder does the actual verification, and shows the checksums and file sizes of both sets of files, alongside each other, and with a Match column that flags any discrepancies. If you are building an unencrypted set of files then there will be lots of differences, while the encrypted files should mostly match (see the Differences section below for more on this).
The binaries in the 4-reference-binaries folder are those extracted from the released version of the game, while those in the 3-assembled-output folder are produced by the build process. For example, if you don't make any changes to the code and build the project with make, then this is the output of the verification process:
Results for variant: gma85-ntsc
[--originals--] [---output----]
Checksum Size Checksum Size Match Filename
-----------------------------------------------------------
cea8c062 18016 cea8c062 18016 Yes COMLOD.bin
442eabc1 18016 442eabc1 18016 Yes COMLOD.unprot.bin
992bbfe6 2980 992bbfe6 2980 Yes ELTA.bin
0f94099a 2426 0f94099a 2426 Yes ELTB.bin
bd3453c7 3252 bd3453c7 3252 Yes ELTC.bin
ff3d3005 3305 ff3d3005 3305 Yes ELTD.bin
a9dfd514 2954 a9dfd514 2954 Yes ELTE.bin
84c77035 4172 84c77035 4172 Yes ELTF.bin
9ec62ad9 4065 9ec62ad9 4065 Yes ELTG.bin
2675f20e 1253 2675f20e 1253 Yes ELTH.bin
51878ce7 932 51878ce7 932 Yes ELTI.bin
08d1c413 2466 08d1c413 2466 Yes ELTJ.bin
7c826b65 6156 7c826b65 6156 Yes ELTK.bin
b7493cd2 25312 b7493cd2 25312 Yes HICODE.bin
d3672d96 25312 d3672d96 25312 Yes HICODE.unprot.bin
42d63335 3789 42d63335 3789 Yes IANTOK.bin
e2edb521 8661 e2edb521 8661 Yes LOCODE.bin
7c92152c 8661 7c92152c 8661 Yes LOCODE.unprot.bin
41dab672 5632 41dab672 5632 Yes LODATA.bin
9f5fee4d 549 9f5fee4d 549 Yes SEND.bin
43f25e32 8077 43f25e32 8077 Yes SHIPS.bin
f5cf6c33 448 f5cf6c33 448 Yes SPRITE.bin
57406380 1024 57406380 1024 Yes WORDS.bin
97ebe9c1 4 97ebe9c1 4 Yes byebyejulie.bin
41e6ba2f 103 41e6ba2f 103 Yes firebird.bin
fd1e9c6d 1096 fd1e9c6d 1096 Yes gma1.bin
c70d57b0 1096 c70d57b0 1096 Yes gma1.unprot.bin
ba6d10a3 290 ba6d10a3 290 Yes gma3.bin
4247ad85 18018 4247ad85 18018 Yes gma4.bin
941dac49 8663 941dac49 8663 Yes gma5.bin
24d06bc5 25314 24d06bc5 25314 Yes gma6.bin
All the compiled binaries match the originals, so we know we are producing the same final game as the Firebird GMA85 NTSC variant.
During compilation, details of every step are output in a file called compile.txt in the 3-assembled-output folder. If you have problems, it might come in handy, and it's a great reference if you need to know the addresses of labels and variables for debugging (or just snooping around).
This repository contains the source code for four different variants of Commodore 64 Elite:
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The Firebird GMA85 NTSC variant, which was the second official release of Commodore 64 Elite from 1986
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The Firebird GMA86 PAL variant, which is identical to the GMA85 version apart from some small changes to make it suitable for PAL systems
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The variant produced by running the build process on the source disk from Ian Bell's personal website
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The variant produced using the binaries from the source disk on Ian Bell's personal website, which differ slightly from the binaries that are produced by running the build process
By default the build process builds the Firebird GMA85 NTSC variant, but you can build a specified variant using the variant= build parameter.
You can add variant=gma85-ntsc to produce the elite-commodore-64-gma85-ntsc.d64 file that contains the Firebird GMA85 NTSC variant, though that's the default value so it isn't necessary. In other words, you can build it like this:
make.bat variant=gma85-ntsc
or this on a Mac or Linux:
make variant=gma85-ntsc
This will produce a file called elite-commodore-64-gma85-ntsc.d64 in the 5-compiled-game-disks folder that contains the Firebird GMA85 NTSC variant.
The verification checksums for this version are as follows:
Results for variant: gma85-ntsc
[--originals--] [---output----]
Checksum Size Checksum Size Match Filename
-----------------------------------------------------------
cea8c062 18016 cea8c062 18016 Yes COMLOD.bin
442eabc1 18016 442eabc1 18016 Yes COMLOD.unprot.bin
992bbfe6 2980 992bbfe6 2980 Yes ELTA.bin
0f94099a 2426 0f94099a 2426 Yes ELTB.bin
bd3453c7 3252 bd3453c7 3252 Yes ELTC.bin
ff3d3005 3305 ff3d3005 3305 Yes ELTD.bin
a9dfd514 2954 a9dfd514 2954 Yes ELTE.bin
84c77035 4172 84c77035 4172 Yes ELTF.bin
9ec62ad9 4065 9ec62ad9 4065 Yes ELTG.bin
2675f20e 1253 2675f20e 1253 Yes ELTH.bin
51878ce7 932 51878ce7 932 Yes ELTI.bin
08d1c413 2466 08d1c413 2466 Yes ELTJ.bin
7c826b65 6156 7c826b65 6156 Yes ELTK.bin
b7493cd2 25312 b7493cd2 25312 Yes HICODE.bin
d3672d96 25312 d3672d96 25312 Yes HICODE.unprot.bin
42d63335 3789 42d63335 3789 Yes IANTOK.bin
e2edb521 8661 e2edb521 8661 Yes LOCODE.bin
7c92152c 8661 7c92152c 8661 Yes LOCODE.unprot.bin
41dab672 5632 41dab672 5632 Yes LODATA.bin
9f5fee4d 549 9f5fee4d 549 Yes SEND.bin
43f25e32 8077 43f25e32 8077 Yes SHIPS.bin
f5cf6c33 448 f5cf6c33 448 Yes SPRITE.bin
57406380 1024 57406380 1024 Yes WORDS.bin
97ebe9c1 4 97ebe9c1 4 Yes byebyejulie.bin
41e6ba2f 103 41e6ba2f 103 Yes firebird.bin
fd1e9c6d 1096 fd1e9c6d 1096 Yes gma1.bin
c70d57b0 1096 c70d57b0 1096 Yes gma1.unprot.bin
ba6d10a3 290 ba6d10a3 290 Yes gma3.bin
4247ad85 18018 4247ad85 18018 Yes gma4.bin
941dac49 8663 941dac49 8663 Yes gma5.bin
24d06bc5 25314 24d06bc5 25314 Yes gma6.bin
You can build the Firebird GMA86 PAL variant by appending variant=gma86-pal to the make command, like this on Windows:
make.bat variant=gma86-pal
or this on a Mac or Linux:
make variant=gma86-pal
This will produce a file called elite-commodore-64-gma86-pal.d64 in the 5-compiled-game-disks folder that contains the Firebird GMA86 PAL variant.
The verification checksums for this version are as follows:
Results for variant: gma86-pal
[--originals--] [---output----]
Checksum Size Checksum Size Match Filename
-----------------------------------------------------------
cea8c062 18016 cea8c062 18016 Yes COMLOD.bin
442eabc1 18016 442eabc1 18016 Yes COMLOD.unprot.bin
992bbfe6 2980 992bbfe6 2980 Yes ELTA.bin
0f94099a 2426 0f94099a 2426 Yes ELTB.bin
bd3453c7 3252 bd3453c7 3252 Yes ELTC.bin
ff3d3005 3305 ff3d3005 3305 Yes ELTD.bin
a9dfd514 2954 a9dfd514 2954 Yes ELTE.bin
84c77035 4172 84c77035 4172 Yes ELTF.bin
9ec62ad9 4065 9ec62ad9 4065 Yes ELTG.bin
2675f20e 1253 2675f20e 1253 Yes ELTH.bin
51878ce7 932 51878ce7 932 Yes ELTI.bin
08d1c413 2466 08d1c413 2466 Yes ELTJ.bin
7c826b65 6156 7c826b65 6156 Yes ELTK.bin
b7493cd2 25312 b7493cd2 25312 Yes HICODE.bin
d3672d96 25312 d3672d96 25312 Yes HICODE.unprot.bin
42d63335 3789 42d63335 3789 Yes IANTOK.bin
e2edb521 8661 e2edb521 8661 Yes LOCODE.bin
7c92152c 8661 7c92152c 8661 Yes LOCODE.unprot.bin
41dab672 5632 41dab672 5632 Yes LODATA.bin
9f5fee4d 549 9f5fee4d 549 Yes SEND.bin
43f25e32 8077 43f25e32 8077 Yes SHIPS.bin
f5cf6c33 448 f5cf6c33 448 Yes SPRITE.bin
57406380 1024 57406380 1024 Yes WORDS.bin
97ebe9c1 4 97ebe9c1 4 Yes byebyejulie.bin
41e6ba2f 103 41e6ba2f 103 Yes firebird.bin
bd5ece7b 1042 bd5ece7b 1042 Yes gma1.bin
b6adf486 1042 b6adf486 1042 Yes gma1.unprot.bin
f5a01242 294 f5a01242 294 Yes gma3.bin
4247ad85 18018 4247ad85 18018 Yes gma4.bin
941dac49 8663 941dac49 8663 Yes gma5.bin
24d06bc5 25314 24d06bc5 25314 Yes gma6.bin
You can build the source disk build variant by appending variant=source-disk-build to the make command, like this on Windows:
make.bat variant=source-disk-build
or this on a Mac or Linux:
make variant=source-disk-build
This does not currently produce a game disk, but instead produces the same binaries as the original build process. In the original development system, these files would then be transmitted from the BBC Micro to the Commodore 64 via a serial link, but that setup isn't emulated here.
The verification checksums for this version are as follows:
Results for variant: source-disk-build
[--originals--] [---output----]
Checksum Size Checksum Size Match Filename
-----------------------------------------------------------
b35e4b7d 18124 b35e4b7d 18124 Yes COMLOD.bin
ca6784f4 18124 ca6784f4 18124 Yes COMLOD.unprot.bin
237ccd96 2977 237ccd96 2977 Yes ELTA.bin
4cf448f2 2426 4cf448f2 2426 Yes ELTB.bin
899dd1a4 3252 899dd1a4 3252 Yes ELTC.bin
5e47acfd 3305 5e47acfd 3305 Yes ELTD.bin
1d1b6a63 2938 1d1b6a63 2938 Yes ELTE.bin
2d1f6439 4142 2d1f6439 4142 Yes ELTF.bin
4c4887f4 4111 4c4887f4 4111 Yes ELTG.bin
8f9317f1 1253 8f9317f1 1253 Yes ELTH.bin
9ba1820f 932 9ba1820f 932 Yes ELTI.bin
b5f82155 2466 b5f82155 2466 Yes ELTJ.bin
d0ee2f81 3222 d0ee2f81 3222 Yes ELTK.bin
5fdb0db0 22369 5fdb0db0 22369 Yes HICODE.bin
eeca286a 22369 eeca286a 22369 Yes HICODE.unprot.bin
42d63335 3789 42d63335 3789 Yes IANTOK.bin
56cbbd68 8655 56cbbd68 8655 Yes LOCODE.bin
7fcc5af9 8655 7fcc5af9 8655 Yes LOCODE.unprot.bin
2771f34f 5632 2771f34f 5632 Yes LODATA.bin
9f5fee4d 549 9f5fee4d 549 Yes SEND.bin
43f25e32 8077 43f25e32 8077 Yes SHIPS.bin
f5cf6c33 448 f5cf6c33 448 Yes SPRITE.bin
52bac547 1024 52bac547 1024 Yes WORDS.bin
You can build the source disk files variant by appending variant=source-disk-files to the make command, like this on Windows:
make.bat variant=source-disk-files
or this on a Mac or Linux:
make variant=source-disk-files
This does not currently produce a game disk, but instead produces the same binaries as the original build process. In the original development system, these files would then be transmitted from the BBC Micro to the Commodore 64 via a serial link, but that setup isn't emulated here.
The verification checksums for this version are as follows:
Results for variant: source-disk-files
[--originals--] [---output----]
Checksum Size Checksum Size Match Filename
-----------------------------------------------------------
58259b1a 18124 58259b1a 18124 Yes COMLOD.bin
39253b9c 18124 39253b9c 18124 Yes COMLOD.unprot.bin
237ccd96 2977 237ccd96 2977 Yes ELTA.bin
4cf448f2 2426 4cf448f2 2426 Yes ELTB.bin
899dd1a4 3252 899dd1a4 3252 Yes ELTC.bin
5e47acfd 3305 5e47acfd 3305 Yes ELTD.bin
1d1b6a63 2938 1d1b6a63 2938 Yes ELTE.bin
2d1f6439 4142 2d1f6439 4142 Yes ELTF.bin
4c4887f4 4111 4c4887f4 4111 Yes ELTG.bin
8f9317f1 1253 8f9317f1 1253 Yes ELTH.bin
9ba1820f 932 9ba1820f 932 Yes ELTI.bin
b5f82155 2466 b5f82155 2466 Yes ELTJ.bin
d0ee2f81 3222 d0ee2f81 3222 Yes ELTK.bin
5fdb0db0 22369 5fdb0db0 22369 Yes HICODE.bin
eeca286a 22369 eeca286a 22369 Yes HICODE.unprot.bin
42d63335 3789 42d63335 3789 Yes IANTOK.bin
56cbbd68 8655 56cbbd68 8655 Yes LOCODE.bin
7fcc5af9 8655 7fcc5af9 8655 Yes LOCODE.unprot.bin
41dab672 5632 41dab672 5632 Yes LODATA.bin
9f5fee4d 549 9f5fee4d 549 Yes SEND.bin
43f25e32 8077 43f25e32 8077 Yes SHIPS.bin
f5cf6c33 448 f5cf6c33 448 Yes SPRITE.bin
57406380 1024 57406380 1024 Yes WORDS.bin
You can see the differences between the variants by searching the source code for _GMA85_NTSC (for features in the Firebird GMA85 NTSC variant), _GMA86_PAL (for features in the Firebird GMA86 PAL variant), _SOURCE_DISK_BUILD (for features in the source disk build variant) or _SOURCE_DISK_FILES (for features in the source disk files variant). You can also search for _GMA_RELEASE for features in both GMA variants, or _SOURCE_DISK for features in all the source disk variants.
The main differences in the GMA86 PAL variant compared to the GMA85 NTSC variant are:
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The disk loaders are different, particularly in the fast loader routine. This does not affect gameplay in any way.
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There is a configuration variable called USA% that you might expect to be set to FALSE for the PAL variant, but it is set to TRUE for both, so this is not a difference between the two variants.
The main differences in the source disk variants compared to the Firebird variants are:
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Some of the game data is stored at different addresses.
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A smaller block of ship data is copied the game loader, though this doesn't make any difference.
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An image containing the build date is included in the disk loader.
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There is no Elite Theme music, only The Blue Danube.
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The joystick is read differently.
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The frequency change when implementing vibrato in voice 3 is different.
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The period when implementing vibrato in voices 2 and 3 is different.
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The music counter stops counting when it reaches 2 rather than 0.
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The format of the music data file is slightly different.
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In the source disk build variant only, the text token for the energy unit is "ENERGY UNIT", rather than the "EXTRA ENERGY UNIT" that is found in all the other variants.
See the accompanying website for a comprehensive list of differences between the variants.
Instead of initialising workspaces with null values like BeebAsm, the original BBC Micro source code creates its workspaces by simply incrementing the P% and O% program counters, which means that the workspaces end up containing whatever contents the allocated memory had at the time. As the source files are broken into multiple BBC BASIC programs that run each other sequentially, this means the workspaces in the source code tend to contain either fragments of these BBC BASIC source programs, or assembled code from an earlier stage. This doesn't make any difference to the game code, which either initialises the workspaces at runtime or just ignores their initial contents, but if we want to be able to produce byte-accurate binaries from the modern BeebAsm assembly process, we need to include this "workspace noise" when building the project. Workspace noise is only loaded by the encrypt target; for the build target, workspaces are initialised with zeroes.
You can disable the production of byte-accurate binaries by passing match=no to the build. This will omit most workspace noise, leaving workspaces initialised with zeroes instead.
Here's an example of how workspace noise is included, from the main source in elite-source.asm:
.LSX2
IF _MATCH_ORIGINAL_BINARIES
IF _GMA_RELEASE
EQUB &76, &85, &9C, &A5, &8B, &85, &9A, &A5
EQUB &8D, &20, &0C, &9A, &B0, &D2, &85, &6F
EQUB &A5, &9C, &85, &70, &A5, &6B, &85, &9B
EQUB &A5, &72, &85, &9C, &A5, &85, &85, &9A
EQUB &A5, &87, &20, &0C, &9A, &B0, &B9, &85
EQUB &6B, &A5, &9C, &85, &6C, &A5, &6D, &85
EQUB &9B, &A5, &74, &85, &9C, &A5, &88, &85
EQUB &9A, &A5, &8A, &20, &0C, &9A, &B0, &A0
EQUB &85, &6D, &A5, &9C, &85, &6E, &A5, &71
EQUB &85, &9A, &A5, &6B, &20, &EA, &39, &85
EQUB &BB, &A5, &72, &45, &6C, &85, &9C, &A5
EQUB &73, &85, &9A, &A5, &6D, &20, &EA, &39
EQUB &85, &9A, &A5, &BB, &85, &9B, &A5, &74
EQUB &45, &6E, &20, &0C, &9A, &85, &BB, &A5
EQUB &75, &85, &9A, &A5, &6F, &20, &EA, &39
EQUB &85, &9A, &A5, &BB, &85, &9B, &A5, &70
EQUB &45, &76, &20, &0C, &9A, &48, &98, &4A
EQUB &4A, &AA, &68, &24, &9C, &30, &02, &A9
EQUB &00, &95, &35, &C8, &C4, &AE, &B0, &FE
EQUB &4C, &F2, &9B, &A4, &47, &A6, &48, &A5
EQUB &4B, &85, &47, &A5, &4C, &85, &48, &84
EQUB &4B, &86, &4C, &A4, &49, &A6, &4A, &A5
EQUB &51, &85, &49, &A5, &52, &85, &4A, &84
EQUB &51, &86, &52, &A4, &4F, &A6, &50, &A5
EQUB &53, &85, &4F, &A5, &54, &85, &50, &84
EQUB &53, &86, &54, &A0, &08, &B1, &57, &85
EQUB &AE, &A5, &57, &18, &69, &14, &85, &5B
EQUB &A5, &58, &69, &00, &85, &5C, &A0, &00
EQUB &84, &AA, &84, &9F, &B1, &5B, &85, &6B
EQUB &C8, &B1, &5B, &85, &6D, &C8, &B1, &5B
EQUB &85, &6F, &C8, &B1, &5B, &85, &BB, &29
EQUB &1F, &C5, &AD, &90, &FB, &C8, &B1, &5B
ELIF _SOURCE_DISK
EQUB &60, &6D, &A5, &8A, &85, &6E, &A5, &8B
EQUB &85, &6F, &A5, &8D, &85, &70, &4C, &40
EQUB &A5, &46, &85, &46, &8B, &46, &88, &A2
EQUB &01, &A5, &71, &85, &6B, &A5, &73, &85
EQUB &6D, &A5, &75, &CA, &30, &FE, &46, &6B
EQUB &46, &6D, &4A, &CA, &10, &F8, &85, &9B
EQUB &A5, &76, &85, &9C, &A5, &8B, &85, &9A
EQUB &A5, &8D, &20, &0C, &A3, &B0, &D2, &85
EQUB &6F, &A5, &9C, &85, &70, &A5, &6B, &85
EQUB &9B, &A5, &72, &85, &9C, &A5, &85, &85
EQUB &9A, &A5, &87, &20, &0C, &A3, &B0, &B9
EQUB &85, &6B, &A5, &9C, &85, &6C, &A5, &6D
EQUB &85, &9B, &A5, &74, &85, &9C, &A5, &88
EQUB &85, &9A, &A5, &8A, &20, &0C, &A3, &B0
EQUB &A0, &85, &6D, &A5, &9C, &85, &6E, &A5
EQUB &71, &85, &9A, &A5, &6B, &20, &E7, &39
EQUB &85, &BB, &A5, &72, &45, &6C, &85, &9C
EQUB &A5, &73, &85, &9A, &A5, &6D, &20, &E7
EQUB &39, &85, &9A, &A5, &BB, &85, &9B, &A5
EQUB &74, &45, &6E, &20, &0C, &A3, &85, &BB
EQUB &A5, &75, &85, &9A, &A5, &6F, &20, &E7
EQUB &39, &85, &9A, &A5, &BB, &85, &9B, &A5
EQUB &70, &45, &76, &20, &0C, &A3, &48, &98
EQUB &4A, &4A, &AA, &68, &24, &9C, &30, &02
EQUB &A9, &00, &95, &35, &C8, &C4, &AE, &B0
EQUB &FE, &4C, &F2, &A4, &A4, &47, &A6, &48
EQUB &A5, &4B, &85, &47, &A5, &4C, &85, &48
EQUB &84, &4B, &86, &4C, &A4, &49, &A6, &4A
EQUB &A5, &51, &85, &49, &A5, &52, &85, &4A
EQUB &84, &51, &86, &52, &A4, &4F, &A6, &50
EQUB &A5, &53, &85, &4F, &A5, &54, &85, &50
EQUB &84, &53, &86, &54, &A0, &08, &B1, &57
ENDIF
ELSE
SKIP 256 \ The ball line heap for storing x-coordinates
ENDIF
Right on, Commanders!
Mark Moxon
