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An assembler for the 6502 microprocessor written in Ruby
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Safiire ac46228b9f I have added many directives, such as .org, ines header, .dw, .bytes, and made it produce proper Roms launch into the entry point at 0xC000 from the reset vector. I basically rewrote the Assembler class, this could still use some cleaning up though, more unit tests, and to compile some code with CHR segments
2015-02-18 03:05:18 -08:00
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lib I have added many directives, such as .org, ines header, .dw, .bytes, and made it produce proper Roms launch into the entry point at 0xC000 from the reset vector. I basically rewrote the Assembler class, this could still use some cleaning up though, more unit tests, and to compile some code with CHR segments 2015-02-18 03:05:18 -08:00
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assembler_6502.rb I have added many directives, such as .org, ines header, .dw, .bytes, and made it produce proper Roms launch into the entry point at 0xC000 from the reset vector. I basically rewrote the Assembler class, this could still use some cleaning up though, more unit tests, and to compile some code with CHR segments 2015-02-18 03:05:18 -08:00
background.asm Initial Commit 2015-02-17 19:05:37 -08:00
beep.asm I have added many directives, such as .org, ines header, .dw, .bytes, and made it produce proper Roms launch into the entry point at 0xC000 from the reset vector. I basically rewrote the Assembler class, this could still use some cleaning up though, more unit tests, and to compile some code with CHR segments 2015-02-18 03:05:18 -08:00
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mario.chr Initial Commit 2015-02-17 19:05:37 -08:00
README.md I have added many directives, such as .org, ines header, .dw, .bytes, and made it produce proper Roms launch into the entry point at 0xC000 from the reset vector. I basically rewrote the Assembler class, this could still use some cleaning up though, more unit tests, and to compile some code with CHR segments 2015-02-18 03:05:18 -08:00

README.md

assembler6502

An assembler for the 6502 microprocessor written in Ruby

6502 Assembler

Usage: ./assembler_6502.rb <infile.asm> -o outfile.nes

This is a pretty straightfoward assembler, that is currently set up to produce iNES ROM formatted binaries from simple assembly listings. It is good at knowing which addressing modes are and are not allowed for each instruction, and contains some examples of correct syntax.

Parsing is done by Regular Expression, because, well the language is so regular, it actually took less time than anything else I've tried to parse in the past, including Scheme using parsec.

It handles labels, and does a two pass assembly, first assembling the byte codes, and then going back and filling in the proper addresses where labels were used.

I have used this to compile some code for the NES, and it ran correctly on FCEUX, got it to make some sounds, etc.

Some Todos:

  • I need to add the .byte operator to add data bytes.
  • I need to add the #<$800 and #>$800 style operators to select the MSB and LSB of immediate values during assembly.
  • I need to make the text/code/data sections easier to configure, it is currently set to 0x8000 like NES Prog ROM
  • I need to add commandline options through the OptionParser library
  • I may make this into a Rubygem
  • I need to split the project up into one class per file like usual.
  • Maybe I can put some better error messages.
  • I should just make a 6502 CPU emulator probably now too.