Patent ID: 7203777

Claim:
A hard disk system that is used as an external storage apparatus of a host device, comprising: a hard disk unit; and a conversion unit which is attachable to and detachable from said hard disk unit, wherein said hard disk unit includes: a hard disk for magnetically storing data; a recording/reading section for recording and reading data to and from said hard disk; and a hard disk side interface section for having data, which is recorded on and read from said hard disk, inputted and outputted to and from said conversion unit in a first transfer format, said conversion unit includes: a host interface section for transmitting and receiving data, which is recorded on and read from said hard disk, to and from said host device in a second transfer format; a conversion unit side interface section for having data, which is recorded on and read from said hard disk, inputted and outputted to and from said hard disk unit in said first transfer format; a transfer format conversion section for carrying out transfer format conversion between said first transfer format and said second transfer format, and for carrying out data transfer between said host interface section and said conversion unit side interface; and a power source section, said hard disk side interface section and said conversion unit side interface are, when said hard disk unit and said conversion unit are connected, made capable of transferring data between each other, and said power source section supplies power to each section of said conversion unit when said hard disk unit and said conversion unit are connected.