VMU (Visual Memory Unit)

The Sega Dreamcast had a peripheral called the VMU (Visual Memory Unit). The VMU is a memory card, but it also has a small (48x32) monochrome display, 4 buttons, and a direction pad.

It's possible to load one game at a time onto a VMU from the Dreamcast, and then take the VMU with you as a handheld gaming device.


I've written an open source assembler/disassembler for the VMU called waterbear (download the latest release from here). You can read the documentation here.

waterbear Screenshot

VMU Development Resources

The Dreamcast Wiki has a lot of resources for VMU development: https://dreamcast.wiki/VMU_development.


The Genesis of waterbear

How waterbear got its start.

Release 0.18.0 of waterbear: .include icon and more

This release adds features to simplify creating VMS headers.

Release 0.2.0 of waterbear: disassemble

Release 0.2.0 of waterbear, which adds the disassemble command

First release of waterbear!

The first release of waterbear, an assembler for the Dreamcast VMU