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...http://www.google.se/patents/US5844776?utm_source=gb-gplus-sharePatent US5844776 - Static memory device having compatibility with a disk drive installed in an electronic apparatus 
