mega65-adventure VS lzsa

What are you on about, can you clarify? Rust can compile in no-std/embedded style just as fine (or better) than C can for basically any ARM or RISCV based processor, and quick googling shows this hal for nearly all pi needs and even MEGA65 is "as supported" (read: not at all officially by anything, fan-only) as any current C compiler. Setting up rust for a new target, so long as the code-gen is supported somehow by LLVM, LLVM plugin, LLVM IR transpiler (and maybe libgcc-jit sort of soon) is just as painful or unpainful as setting up a whole team to work via C/C++ with comparable testing harnesses. This doesn't mean easy and is an area Rust is still improving rapidly by the various enterprise agencies (Ferrous systems, Oxide, more I can't remember...) who specifically want to bring rust to such low end hardware because frankly both C and C++ suck with vendor proprietary tool chains and quirks.

True.

If you're on your way down this rabbit hole, there's a bunch of old-machine-specific compression algorithms, developed by the emulator community, e.g. LZSA: https://github.com/emmanuel-marty/lzsa

There's quite a lot of retro modern LZ activity too! LZ turns out to be amazing on old machines, often only several times slower than a block copy. Optimal compressors and control over the algorithm have led to some very tight demos.

https://www.brutaldeluxe.fr/products/crossdevtools/lz4/index... LZ4 Data Compression - a rather long and in-depth article looking at LZ4 on the 65816 for the Apple IIgs

https://github.com/emmanuel-marty/lzsa - LZSA - a LZ4-like modern LZ that's more efficient both in speed and compression to LZ4 (at least on the 8 bitters it targets).