Inside the Disk Drive Chassis
Lifting the top off of the disk drive housing exposes a battery compartment. Accessible from a door on the top of the unit, this compartment holds six C-cell batteries. The drive also accepts power from an AC adapter, but Nintendo included the battery option in case the Famicom and a TV set already occupied the nearest power outlet.
Below the battery compartment is the disk drive mechanism itself, which you'll see more of in a moment.