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js65


Advanced 6502 assembler with patching support based on ca65 syntax

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What is js65

Written in TypeScript, js65 intends to be an almost fully compatible ca65-style assembler, but with many new features to make patching roms a breeze. Whether you are making a homebrew NES game, a romhack, or a randomizer, js65’s power additions on top of the baseline ca65 features makes your life easier.

For Homebrew
Auto pack banks with cross bank placement
For Romhacks
Assembler controlled linker placements
For Romhacks
Free space tracking for squeezing patches everywhere possible
For Randomizers
Use as a library to programatically configure the output