Patent ID: 8464015

Claim:
A portable arithmetic processing device, comprising: a communication control unit to receive predetermined information transmitted from an external device; a data storage unit to include a first data readable/writable memory; a power supply unit to drive the arithmetic processing device; and a control unit to determine, when receiving the predetermined information, an area in which the data stored in the first memory shall be erased corresponding to a battery residual quantity of the power supply unit and to control and execute a data erasing process with respect to the thus-determined area, wherein the first memory is configured to be partitioned into a plurality of partitions, the control unit selects and implements any one of a first processing mode of executing the erasing process in a way that determines an area recorded with partition information in the first memory as the shall-be-erased area and a second processing mode of executing the erasing process in a way that determines data area within the partition as the shall-be-erased area, and the control unit implements the first processing mode if the battery residual quantity is smaller than a fixed quantity, and implements the second processing mode if the battery residual quantity is equal to or larger than the fixed quantity, the control unit, when implementing the second processing mode, after erasing the partition information by executing the erasing process with respect to the area stored with the partition information of the first memory, executes the erasing process with respect to the data area within the partition of which the partition information is erased, further comprising a second data readable/writable nonvolatile memory, wherein the control unit, when performing the erasing process in the second processing mode, executes the erasing process on a per sector basis with respect to the data area within the partition, further determines whether the battery residual quantity of the power supply unit is equal to or larger than a predetermined quantity each time the erasing process is performed on the per sector basis, and writes the information kept during the execution of the erasing process and address information of an already-erased sector, as pieces of erasing process information, to the second memory when the battery residual quantity is smaller than the predetermined quantity, and terminates the erasing process midway in the second processing mode.