Abstract: A semiconductor disk wherein a flash memory into which data is rewritten in block unit is employed as a storage medium, said semiconductor disk comprises a data memory in which file data are stored, a substitutive memory which substitutes for blocks of errors in the data memory, an error memory in which error information of the data memory are stored, and a memory controller which reads data out of, writes data into and erases data from the data memory, the substitutive memory and the error memory. Since the write errors of the flash memory can be remedied, the service life of the semiconductor disk can be increased.

Abstract: A control method and system when a flash memory is used as a semiconductor disk or a main memory in an information processing system. A semiconductor file system comprises a first nonvolatile memory electrically erasable, a second nonvolatile memory not electrically erasable, a volatile memory, a controller which controls the memories, and a control section which controls the controller wherein a physical address corresponding to a logical address specified from an external system is accessed. The first nonvolatile memory stores data for the external system to perform operations, first management information indicating the correspondence between physical addresses at which the data is stored and logical addresses, and second management information indicating a state of the first nonvolatile memory. The second nonvolatile memory previously stores interface information required for inputting and outputting the data from and to the external system and read-only data of the data.

Abstract: A semiconductor storage device such as a disk pack includes a plurality of flash memories, a write buffer memory in which data are temporarily held, a processor which controls data writing and erasing operations and which transfers and analyzes commands and statuses to and from the flash memories, and a circuit which generates a writing supply voltage Vpp for the flash memories. The semiconductor disk pack may be connected, for example, to a standard bus in a personal computer. The processor operates to send a first instruction for writing or erasing data of one word into a first one of the flash memories, and it continuously writes the data of one word into an accessible one of the other flash memories before the first one of the flash memories becomes capable of accepting the next write or erase instruction.

Abstract: A battery power supply system for supplying DC electric power to a DC operated apparatus includes an AC/DC adapter for converting AC electric power into DC electric power, a plurality of batteries and a battery charger for charging the plurality of batteries. The battery power supply system includes a plurality of charge lines for connecting the battery charger to the plurality of batteries and a plurality of discharge lines connected to outputs of the plurality of batteries. Switches are provided in each of the plurality of charge lines and discharge lines.