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Dumping the Sega Dreamcast VMU ROM (20 Years Later)

Teddy Rogers

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Teddy Rogers

Dumping the Sega Dreamcast VMU ROM (20 Years Later)


Back in 1999, SEGA released the VMU. It was a companion to the dreamcast - a smart memory card for saved games that also had some buttons, a buzzer, and a screen, so that it itself could be used for mini-games. Inserted into the controller, the VMU acted as a second screen. Standalone, it ran off its two CR2032 batteries and allowed save game file management, minigames, and simple animations. The VMU could store one single game (mandatorily starting at flash address 0) and multiple datafiles. A relatively large community sprang up around the VMU in the early 2000s, with a few homebrew games made, and some features documented. Later, some official documents appeared online from SEGA, and then the world lost interest.

Currently, one may get a VMU on eBay for $3, with free shipping. This got my attention, so I got one. Sadly, most of the websites dealing with VMU hacking from the 2000s are long gone. Web Archive only has a few archived (they have a terrible tendency to honor "robots.txt" from 2010 on content collected before it existed, so any domain that is resold usually causes old archives to be deleted). I did find the official documentation for the VMU (googling for "vmu.pdf" mirrored here helped) and pieces of the official dev kit. Over the next month I uncovered most of the VMU's secrets and today I present them here, together with the most practical way to program a VMU to date. The official doc that I mentioned above is mandatory reading if you intend to program the VMU.

http://dmitry.gr/index.php?r=05.Projects&proj=25. VMU Hacking


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cool post. if you've got some time to kill, i really recommend watching this too. It's awesome to see the snapshots of him reversing the protection functions in the firmware in IDA :D


Love me some hardwares hacking!


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