MOS 6510

A Ruby gem emulating the MOS 6510 microprocessor found in the Commodore 64. The processor has the same instruction set as the MOS6502 which is found in other entertainment systems.

Additionally, the gem allows you to supply an object which simulates the SID processor (Sound Interface Device - the sound chip from the Commodore 64). This object will receive poke calls whenever the simulated program writes to the addresses mapped to the SID.

Be warned: This is just a very raw conversion of a JavaScript implementation stolen (*) from the jsSID project. It has bugs, probably because of my conversion. I'd love fix this one day, but just needed a MOS 6510 emulator for another project.

(*) This explains the GPL v2 license of this project.

require 'mos6510'

class MySid
  def poke(address, value)
    puts "SID address #{address} set to value #{value}"
  end
end

instructions = [
  # MOS 6510 instructions as an array of bytes
]

# If you don't want to simulate a SID, just leave that out
cpu = Mos6510::Cpu.new(sid: sid)
# Read the instructions in the memory, starting at location 500
cpu.load(instructions, from: 500)
cpu.start

# Jump to address 500, and hope that your program will return sometime
cpu.jsr(500)

# If your program left a result in the memory, look at the contents of an address
puts "Memory address 1300 contains #{cpu.peek(1300)}"

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/olefriis/mos6510.

The gem is available as open source under the terms of the GPL V2 License.