Static memory device having compatibility with a disk drive installed in an electronic apparatus

Abstract

A static memory device has compatibility with a disk drive installed in an electronic apparatus as an external storage unit. The static memory device has a first memory board arranged on the same base portion as the one on which the disk drive can be installed, the first memory board having the same projected area as the disk drive. On the first memory board is arranged a storage unit which is accessible at high speed, such as a semiconductor memory. When the storage capacity of the first memory board only is not enough, an extension memory board can be mounted on the first memory board. When the storage capacity is not sufficient even by mounting the extension memory board on the first memory board, a second memory board can be mounted on the extension memory board. Extension memory boards can also be mounted on the second memory board. Even in this state, the shape is the same as that of the disk drive. Therefore, the user is allowed to select either the disk drive or the static memory device and to mount it in the electronic apparatus as an external storage unit.

Dependencies are inferred from the claim text.