Explorations in ZX Spectrum programming
This is an attempt by Djaybee from the MegaBusters to write some form of demo for ZX Spectrum.
There's a loader file, loader.bas, written in BASIC, which
then loads binary files, in order:
preload.asm clears the screen and sets up the screen attributes
before loading the splash screen. The attributes are set first
such that the splash screen is loaded directly with the right colors.
splash.bin is the splash screen itself, directly in the format of
the framebuffer bitmap.
mbzx124.asm is the main code, loaded after the splash screen.
This code is being developed with the following tools:
- At build time:
- To run the code:
- As a development environment:
The ZX Spectrum doesn't support binary executables, it boots into a BASIC interpreter and, from there, can only directly load and interpret BASIC code.
To get into a binary, the BASIC interpreter first needs to load the binary in RAM, and then invoke it, which is typically done by a "loader" BASIC program that is packaged with the actual binary.
Furthermore, the BASIC interpreter on the ZX Spectrum is always tokenized, it can't handle ASCII inputs. That means that the BASIC program, as source code, needs to be processed into its tokenized form.
On top of that, the ZX Spectrum uses tape as its primary storage medium, such that we have to deal with tape images.
zmakebas tokenizes BASIC from source code, and outputs directly a tape image.
zasm assembles our code into a raw binary. bin2tap turns that binary into a Spectrum tape image.
Tape images can be concatenated (just like real tapes!)
The demo in this repository is licensed under the terms of the AGPL, version 3 or later, with the following additional restriction: if you make the program available for third parties to use on hardware you own (or co-own, lease, rent, or otherwise control,) such as public gaming cabinets (whether or not in a gaming arcade, whether or not coin-operated or otherwise for a fee,) the conditions of section 13 will apply even if no network is involved.
As a special exception, the source assets for the demo (images, text, music, movie files) as well as output from the demo (screenshots, audio or video recordings) are also optionally licensed under the CC BY-SA 4.0 License. That exception explicitly does not apply to source code or object/executable code, only to assets/media files when separated from the source code or object/executable file.
Licensees of the a whole demo or of the whole repository may apply the same exception to their modified version, or may decide to remove that exception entirely.
This code doesn't have any privacy implications, and has been written without any thought about the privacy implications that might arise from any changes made to it.
Let's be honest, if using a demo on such an old computer, even emulated, causes significant privacy concerns or in fact any privacy concerns, the world is coming to an end.
None of the code in this project processes any personal data in any way. It does not collect, record, organize, structure, store, adapt, alter, retrieve, consult, use, disclose, transmit, disseminate, align, combine, restrict, erase, or destroy any personal data.
None of the code in this project identifies natural persons in any way, directly or indirectly. It does not reference any name, identification number, location data, online identifier, or any factors related to the physical, psychological, genetic, mental, economic, cultural or social identity of any person.
None of the code in this project evaluates any aspect of any natural person. It neither analyzes nor predicts performance at work, economic situation, health, personal preferences, interests, reliability, behavior, location, and movements.
_Don't use this code where GDPR might come into scope. Seriously. Don't. Just don't.
Generally speaking, the code in this project is inappropriate for any application where security is a concern of any kind.
Don't even think of using any code from this project for anything remotely security-sensitive. That would be awfully stupid.
In the context of the Sinclair ZX Spectrum, the hardware is far too primitive to support any notion of security at the assembly level, and assembly as a language is as far from being secure by default as can be.
None of the code in this project involves any direct or indirect logical or physical data connection to a device or network.
Also, all of the code in this project is provided under a free and open source license, in a non-commercial manner. It is developed, maintained, and distributed openly. As of November 2024, no price has been charged for any of the code in this project, nor have any donations been accepted in connection with this project. The author has no intention of charging a price for this code. They also do not intend to accept donations, but acknowledge that, in extreme situations, donations of hardware or of access to hardware might facilitate development, without any intent to make a profit.
This code is intended to be used in isolated environments. If you build a connected product from this code, the security implications are on you. You've been warned.
The intended use for this code is not a critical application. This project has been developed without any attention to the practices mandated by NIS2 for critical applications. It is not appropriate as-is for any critical application, and, by its very nature, no amount of paying and auditing will ever make it reach a point where it is appropriate. The author will immediately dismiss any request to reach the standards set by NIS2.
Don't even think about it. Seriously. I'm not kidding. If you are even considering using this code or any similar code for any critical project, you should expect to get fired. I cannot understate how grossly inappropriate this code is for anything that might actually matter.