Abstract: A portable memory device that supports exchange of stored data directly is disclosed. The memory device has an I/O controller embedded with two interface conversion mechanisms, a flash memory unit connected to the I/O controller, a USB interface and an auxiliary I/O interface respectively connected to the I/O controller, and a power unit to supply operating power. Since the I/O controller is powered, the memory device can be connected to another same type memory device through the auxiliary I/O interface for direct exchange of stored data, without need of passing through a host computer or other equivalent electronic device with data exchange capabilities through a USB port. Further, a microprocessor embedded with a format-specific interface conversion mechanism is installed between the auxiliary I/O interface and the flash memory, while the original I/O controller is not altered.