The original source for the 1981 masterpiece “Defender” is now on Github! #Gaming #Arcade

The original source for Eugene Jarvis and Sam Dicker’s 1981 masterpiece “Defender” has been put on GitHub this week!

The source code can be assembled into an executable that you can then run in Windows or Linux. You can also assemble it into the 11 rom files that would have been loaded onto the arcade cabinet’s ROM board. Today, these rom files can be used to play the game in an emulator such as MAME.

The game source code for Defender in /src was originally retrieved from It is the Motorola 6809 assembly language source code for the ‘Red Label’ version of the game.

The source code for the sound module was retrieved from

Since the RASM assembler is no longer available to us we use asm6809 instead. Fortunately this does a good job of assembling the source faithfully and only very minor modifications to the source files are required to produce binaries.

Check out the GitHub repo for details.

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1 Comment

  1. Just wanted to see if I pass the resistor captcha.

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