A storage device is designed for use with a personal computer system and formed of a RAM module connected with a power unit, and a memory accessing unit which is intended to access data in the RAM module and is connected with a data accessing interface serving as a data accessing interface between the storage device and the personal computer system. The memory accessing unit and the data accessing interface are connected with a command translating unit which is intended to translate a control machine code of the hard disk of the personal computer system into a control machine code of the memory accessing unit. The booting of the personal computer system and the executing of application programs by the personal computer system are accelerated by the storage device.