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Space Invaders arcade machine

This is a Clash implementation of the 1978 Space Invaders arcade machine by Taito.

This code is part of the book Retrocomputing with Clash: Haskell for FPGA Hardware Design at https://unsafePerform.IO/retroclash/.

Click to play YouTube video

Hardware architecture

Clash implementation

Limitations

This implementation doesn't aim to be cycle-accurate; it wouldn't matter for much anyway, since the CPU runs at the VGA output pixel clock of 25 MHz, whereas the real cabinet ran at 2 MHz. Luckily, Space Invaders does all animations keyed to two 60 Hz timers triggered by the video system.

Sound is not implemented at all.

The back-panel DIP switches are not yet mapped to anything.

Building

Included are rudimentary Shake rules to build for various hobbyist FPGA dev boards:

Make a file called build.mk with content similar to the following:

TARGET = papilio-pro-arcade
ISE = ~/prog/docker/xilinx-14.7-ubuntu-12.04/run
VIVADO = ~/prog/docker/xilinx-2019.1-ubuntu-18.04/run
QUARTUS = ~/prog/quartus/wrapper.sh --

The ISE, VIVADO, and QUARTUS fields are to optionally wrap invocations of the Xilinx ISE / Vivado and Intel Quartus toolchains in case you want to run them via Docker, Nix, shell scripts that set some environment variables, etc.

Then you can build for the Papilio Pro by running the included mk script.

Useful links