NES to SNES Porting Template

A template and (hopefully) useful routines for porting NES games to the SNES

Prerequisites

• cc65 - the 65c816 compiler and linker

Other Userful Tools I've used for this project

• Mesen2 - A fantastic emulator for development on a bunch of platforms
• HxD - A Hex Editor
• Visual Studio Code - Used as the development environment

Structure of the Project

• bankX.asm - The NES memory PRG banks, there are 8 of them. This code is heavily edited/altered for the port

• chrom-tiles-X.asm - The NES CHR ROM banks, also 8 of them. These are untouched aside from converting them to the SNES tile format that we use. The go script takes care of that for you.

• 2a03_xxxxx.asm - Sound emulation related code

• bank-snes.asm - All the code that runs in the A0 bank, this is where we put most of our routines and logic that we need that is SNES specific. Also includes various included asm files:

  • attributes.asm - dealing with tile and sprite attributes
  • hardware-status-switches.asm - various useful methods to handle differences in hardware registers
  • hud-hdma.asm - HDMA logic for the player health bars and names to be shown
  • intro_screen.asm - Title card that is shown at the start of the game
  • palette_lookup.asm and palette_updates.asm - palette logic
  • sprites.asm - sprite conversion and DMA'ing

• main.asm - the main file, root for the project

• vars.inc, registers.inc, macros.inc - helpful includes

• resetvector.asm - the reset vector code

• hirom.cfg - defines how our ROM is laid out, where each bank lives and how large they are

Building

• Update the build.sh file with the location of your cc65 install
• make sure you've extracted and copied the rom banks to /src
• port all the changes you need to port! (magic)
• run build.sh
• The output will be in out/