The VMU is plugged directly into one of two slots on a Dreamcast controller. Two VMUs may be plugged in each controller. When operated independently of the Dreamcast console, the VMU acts as a file manager with limited game console functionality. VMUs may also connect to each other directly to facilitate file transfer or multiplayer gaming. The VMU runs on two CR-2032 lithium batteries which are inserted into the rear of the VMU under a screw-secured lid. Without battery power, the VMU still works as a memory card and auxiliary display, but cannot play downloaded mini-games.