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The VMU, or Visual Memory Unit, is an accessory for the Sega Dreamcast which functions primarily as a storage device for save files. During gameplay, a VMU attached to a controller may display additional helpful information for the game or just the game's logo. The VMU can be used independently of the Dreamcast to manage save data or play mini-games downloaded from full Dreamcast games.

Technical Specifications

CPU 8-bit (Sanyo LC8670 "Potato")
Memory 128KB flash memory. 28KB is reserved for system use leaving 100KB for data storage, which is divided into 200 'blocks' - 1 block equaling 512 bytes.
Display 48 dot width × 32 dot height, LCD
Display size (width×height): 37 mm × 26 mm (1.46 in × 1.02 in)
Case dimensions (width×height×depth): 47 mm × 80 mm × 16 mm (1.85 in × 3.15 in × 0.63 in)
Power source* 2 × CR2032 batteries (6V) with auto-off function
Sound 1-channel PWM sound source
Weight 45 g (1.6 oz)
  • The batteries are NOT required to maintain game saves; those are kept in flash memory. They are required only to use the VMU independently of the Dreamcast to play minigames, manage save files, and keep time.

Internal Hardware


Power Supply Mod

The VMU is normally powered by two CR2032 batteries which can drained after only a couple hours of use. Because the VMU requires a voltage of 6VDC, one can be modified to be powered by 4 AAA or AA batteries or a suitable AC adapter. See the VMU Power Supply Mod page for a guide on how to do this simple mod yourself.