In this post I will describe a small electronics project designed to enable the remote programming of a real Commodore 64 that is switched on and running. To achieve this, several parts are involed, utilising some custom circuitry and communications protocol, a Raspberry Pi, a C program, a 6502 assembler program and a little F# program to finish it off.
In this post we will see how asi64’s (Racket’s) macro system can massively reduce the amount of 6502 assembly code you have to write, beyond what a typical macro assembler can achieve.
In this post we will see how asi64 is more than your average macro assembler, by combining arbitrary disk io, functional programming techniques and code generation alongside your typical 6502 assembly code. The aim is to create a very simple sprite animation viewer, that writes the resulting C64 program by interleaving file parsing and machine code generation.
Here’s the program displaying some sprites that @silverspoon has started working on :) (in different, single colours for the fun of it)
In my last few posts, I detailed some of my experience learning 6502 assembler for the Commodore 64. I started off using DASM, which seems to be quite a nice assembler, severely lacking in documentation. Then I discovered the very awesome KickAssembler, which includes a full blown scripting language on top of java, lots of other very nice features, and great documentation. This made me realise what a powerful modern assembler could be like - and perhaps I could go one step further with it.
Asi64 extends Racket to become a 6502 assembler. No need for scripting languages or half baked macro systems here - you have literally all of Racket and its amazing macro system on your side. It also has direct support for Vice, a popular Commodore 64 emulator, passing your labels and breakpoints along enabling a fluid programming and debugging cycle. Hats off to the fantasic KickAssembler, I have stolen many ideas from it :)
