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FPGA implementation of Robotron: 2084

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README.md

robotron-fpga

An implementation of the classic Robotron: 2084 video arcade game from 1982. Both the sound board and CPU/interface boards are implemented, but are in separate sub-projects at the moment. The CPU/interface implementation relies on a Motorola MC6809E processor attached to the FPGA board via an adapter board design that is part of this project.

robotron-cpu on NEXYS2 FPGA board

The goal is to have a complete Robotron: 2084 game implemented in a single, compact, inexpensive FPGA board which includes the necessary peripherals: video and sound outputs, joysticks interface, and coin/player buttons.

Status

The CPU/interface and sound boards are implemented as separate projects. Both appear to function well.

The MC6809E breakout board has been fabricated, but has some design issues that need to be addressed. The primary issue is the lack of pull-up/-down resistors on key MC6809E signals, to keep the processor in a RESET state until the FPGA board is ready to work with the MC6809E. I also screwed up and put the NEXYS2 connector on the "bottom side" of the board. Smooth!

Documentation

These documents served me well during development of this project.

Sean Riddle - Williams arcade machine information, including Robotron: 2084.

Robotron-2084 - Williams arcade machine official documentation.

Documentation for various ICs in the original Robotron: 2084 machine.

Digilent - FPGA development boards and accessories.

Xilinx - FPGA silicon and tools vendor.

Requirements

  • Digilent NEXYS2 Spartan-3E FPGA development board.

    This is the board I've done my development on, and is a good choice because it has plenty of inputs, a VGA output connector, many switches and LEDs, and enough onboard RAM and flash to meet the game's memory needs.

  • Williams Robotron: 2084 ROM binary files:

    These files are often used with MAME, the arcade emulator. CPU board ROM files are named "robotron.sb?", where "?" is "1" through "9" and "a" through "c". The sound board ROM file is named "robotron.snd".

  • Python 2.7:

    Used to transform ROM and PROM files into VHDL files.

  • Xilinx ISE WebPack 13.4:

    For compiling VHDL and generating the bit file for the FPGA.

  • Digilent Adept or other JTAG tool:

    For loading the bit file into FPGA board.

  • VGA monitor:

    Video output is 31.25 kHz horizontal sync and 60 Hz vertical sync, which is compatible with VGA monitors. The output is line-doubled from the arcade game's original 15.625 kHz horizontal sync.

  • RC lowpass filter:

    The PWM audio output from the FPGA needs filtering to sound reasonable, or an eight-bit DAC can be attached to the 8-bit audio output pins of the FPGA board.

Tools

  • make_rom_file.py:

    Translates a set of Robotron ROM board ROM files (like those you would use with the MAME arcade emulator) into a binary file that can be loaded into the flash device on the Digilent FPGA board.

  • make_decoder_vhdl.py:

    Translates a decoder.4 or decoder.6 file (data dumped from decoder PROMs on the Robotron CPU board) into a VHDL file used by the robotron_cpu project.

  • dac_out_wave.py:

    Translates the text file output of robotron_test.vhd into a WAV file that can be played.

  • make_sound_rom.py:

    Produces rom_snd_blocks.vhd, containing VHDL ROM blocks, from the contents of a robotron.snd ROM file. The robotron.snd file is not provided due to copyright on the original ROM binaries produced by Williams. I happen to have a physical instance of the ROM board, so I'm in the clear. :-)

Contributing

Contributions are welcome!

Please respect Williams Electronics' copyright and do not post any VHDL or .bit files containing their binary code.

License

This hardware design is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

The associated software is provided under the GNU Public License, version 3:

This project is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This project is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this project. If not, see http://www.gnu.org/licenses/.

Contact

Jared Boone jared@sharebrained.com

ShareBrained Technology, Inc.

http://www.sharebrained.com/

The latest version of this repository can be found at https://github.com/sharebrained/robotron-fpga

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