MEGA65 Symbols

This repo provides MEGA65 I/O register symbol definition files for several major assemblers and C compilers. It also provides a tool for generating new ones from the iomap.txt file, which itself is generated from the VHDL implementation of the chips.

Note: Future updates to the tool and to the MEGA65 iomap.txt may result in symbol name changes. I recommend downloading or making symbol files at the beginning of a project, and then not updating them for the lifetime of that project. Your patience is appreciated. :)

Why?

When writing assembly language code for the MEGA65 personal computer, you will need to make regular use of addresses for the machine's input/output registers. These addresses are documented as hexadecimal values in the official documentation. Typically, you find the register you need in the manual, then copy the address into your program, usually assigning it to a symbol to make your code easier to read.

VIC2_BORDERCOL_ADDR = $D020

* = $C000
loop:
    inc VIC2_BORDERCOL_ADDR
    jmp loop

All such registers already have names and known addresses. These are used to produce the tables of documentation in the first place. We might as well use a tool to generate a file that already contains all of these symbols to make them easier to use during programming.

What?

I wrote a tool that generates symbol definition files for major assemblers and C compilers used for MEGA65 programming. It takes as input the iomap.txt file produced by the mega65-core project.

For convenience, I have committed the output from this tool directly in this repo, generated on the date listed in the file. I don't promise to keep these up to date, but they're probably useful as is.

• mega65_io.a : ACME assembler
• mega65_io.asm : [Kick Assembler]http://theweb.dk/KickAssembler/Main.html#frontpage)
• mega65_io.s : ca65 assmebler
• mega65_io.h : cc65 C compiler
• mega65_io.oph : Ophis assembler
• mega65_io.rs : Rust compiler

How?

To get the latest iomap.txt and run the tool to generate new symbol files:

gh repo clone MEGA65/mega65-core
cd mega65-core
make iomap.txt

python3 ../mega65-symbols/make-m65-symbols.py --format=acme

Run the tool with --help for more information about running the tool.

Once you have the appropriate file to your project directory, use the assembler/compiler syntax to include it in your project.

!source "mega65_io.a"

* = $C000
loop:
    inc VIC2_BORDERCOL_ADDR
    jmp loop

Who?

Hi, I'm Dan! Please file an issue with any feedback you have on this tool or the files it produces.