FPG-8 is an implementation of Chip-8/S-Chip language for FPGAs using Verilog.
It was developed as a project for the ECE-574 course at Worcester Polytechnic Institute.
It definitelly is not the fastest or more optimized implementation, but it works pretty well.
It was written for the Nexys 3 board, but should work well on other boards.
All the interaction with the system is done through the USB serial port and the game output is shown on a VGA display. Sound is generated using the Digilent DA1 Module connected to pins 1-6 of the PmodA port of the Nexys 3.
If you don't care about all the nerdy stuff in the following sections, you can simply download the binaries. The binary distribution contains the Java application compiled in a JAR file and a bit file to program your board using, for example, Adept.
The complete Verilog code is available under the verilog folder. It was developed using the ISE tools from Xilinx. It uses some cores from the IP Core Generator, specially the Microblaze microcontroller that handles the serial communication.
The Microblaze is programmed in C and the source is available under the c folder. Here's an excelent tutorial about how to merge the C code into the bit file before programming the FPGA.
It's impossible to play games typing commands to a serial port, so I wrote a Java application that uses the serial port to load the games, capture user input and also control the debugger. The complete code is under the java folder. It uses Maven to handle dependencies, except for the SteelCheckbox, that is not available on the Maven Repository.
The application searches for games under the games folder on the application's directory. Games are stored in a ZIP file containing a rom.ch8 file that is the Chip-8 ROM, a logo.png file that contains a 80x80 picture that is shown on the menu on the left, a screenshot.png file that contains a 510x253 picture that is shown on the center when the came is selected and a description.json file that contains some information about the game in JSON format. The slowdown should not be greater than 65535, because it's a 16-bit number. The mapping parameter maps the Chip-8 keyboard to your keyboard. Any letter is valid and also the special values arrow-up, arrow-down, arrow-left, arrow-right, ctrl, alt, shift, enter and space.
After days of Verilog development, I really wanted to play some games, so this application was written very fastly. It can't handle board disconnections, permission errors or any other thing your evil mind can think of.
I included the source for a simple application I wrote to test some opcodes of my implementation. It's available under the asm folder. It can be assembled by the Mochi8 Assembler.
There is also a program that writes "Thank You!" on the screen, that I used in the end of the project presentation.
Under the docs folder there are the slides I used for the presentation of this project.
There is also the project report that describes the implementation in details. Section 2 of the report summarizes all the information I could find about the Chip-8 on the web and can be used as a documentation for your own implementation.
Under the misc folder you can find a OpenOffice Calc spreadsheet that I created to help me drawing the font for the "Thank You" program.
I'd like to thank Professor R. James Duckworth for the great VHDL/Verilog course and the opportunity to develop this project and Boyang Li for being a great TA.