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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[edit]

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[edit]


Power Supply Mod[edit]

Main article: VMU 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.