MEGA65 C Tutorial

This repository aims to demonstrate how to compile C programs that target the computer using any of the C tool-chains that are currently available for that platform: , and .

Overview

The Makefile contains targets for installing and updating the tool-chains (SDK) and the MEGA65 emulator (XEMU), compiling the example programs (one at a time), as well as running them in .

This should give a starting point for experimentation and exploration, help in gaining an overview of available options and provide a low friction entry into cross-compiling C programs for the MEGA65.

Prerequisites

This tutorial assumes running on a POSIX compatible operating system and that java, git, curl, unzip, gcc and make are available.

Note: Windows users may try to build using , but will need to manually install maven (get the zip archive and unpacked it directly into /usr/local of your msys2 installation), as well as installing SDL2, git and unzip via pacman (something like pacman -S mingw-w64-x86_64-SDL2 unzip git might do the trick here. Additionally it might be necessary to add the location of the (locally installed) java runtime to the PATH variable with something like: export PATH=/c/path/to/your/jdk/bin:$PATH in ~/.bash_profile. YMMV, though.

Quick start

Clone repository: git clone https://github.com/everslick/mega65-c-tutorial.git
Change directory: cd mega65-c-tutorial
Install tool-chains and Xemu: make setup
Compile and run hello world: make cc65 or make kickc or make vbcc
GOTO 4

Usage

So how does this tutorial work anyway? Each lesson tries to focus on one specific issue or feature and is accompanied by an example program that must be compiled with make PRG=XX YYY where XX is a two digit number (e.g. 05) and YYY is the compiler you want the program to be built with (e.g. cc65).

If the build was successful, Xemu will be started automatically and the program will be injected and launched in Xemu. When you close the Xemu window the program binary and all its build artifacts (like object files and similar) get deleted and you can recompile the same program with a different compiler or compile a different program.

Examples

In the following section each example program gets a short description and compares and contrasts the differences between the compilers, as well as possible issues with a particular tool-chain.

Example 01 (hello world)

The simplest possible exercise most programmers try when learning a new language: The infamous hello, world! program. Simple as it is, it already demonstrates multiple issues and differences between all compilers.

Source:

#include <stdio.h>

int main(int argc, char **argv) {
  printf("hello, world!\n");

  return (0);
}

Build: make PRG=01 vbcc

Example 02 (hello world refined)

Example 02 tries to rectify the differences and issues raised in example 01 by taking some precausions before printing to the screen.

Source:

#include <stdio.h>

#define _mkstr_(_s_)  #_s_
#define mkstr(_s_)    _mkstr_(_s_)

#define POKE(X,Y) (*(unsigned char *)(X))=Y
#define PEEK(X)   (*(unsigned char *)(X))

static void togglecase(void) {
#ifdef __KICKC__
  POKE(0xD018, PEEK(0xD018) ^ 0x02);
#endif
}

int main(int argc, char **argv) {
  togglecase();

  printf("hello, world!\n\n");
  printf("PROGRAM=%s, VERSION=%s, TOOLCHAIN=%s\n",
    mkstr(PROGRAM), mkstr(VERSION), mkstr(TOOLCHAIN)
  );

  return (0);
}

Build: make PRG=02 kickc

Available make targets

help print this help
clean remove stale build artifacts
setup install/update tool-chains and Xemu
kickc compile with KICKC
cc65 compile and link with CC65
vbcc compile and link with VBCC

Resources

Discussion & Help:

Contributors

Croccydile (testing on MSYS2, finding typos)

ToDo

More lessons (example programs)
Better code documentation

Suggestions, bug reports, and pull requests are very welcome!

everslick/mega65-c-tutorial