Memory card and host device thereof

A method of controlling a storage device including a command terminal;

• a plurality of data terminals;
• a clock terminal;
• a power terminal for a power supply voltage;
• a ground terminal for a ground voltage;
• and a nonvolatile memory,
• the method comprising:
• receiving a clock signal through the clock terminal from an outside of the storage device;
• latching data received through at least one of the data terminals from the outside of the storage device, in accordance with only one of a rising edge and a falling edge of the clock signal, in a first transfer mode;
• latching data received through at least one of the data terminals from the outside of the storage device, in accordance with both the rising edge and the falling edge of the clock signal, in a second transfer mode;
• receiving a first command of a check function whose mode bit being a first value through the command terminal;
• outputting first status data that includes information indicating that the storage device supports the second transfer mode, through one of the data terminals to the outside of the storage device, in response to the first command of the check function whose the mode bit being the first value;
• receiving a first command of a set function whose the mode bit being a second value through the command terminal from the outside of the storage device;
• setting the storage device into the second transfer mode in response to the first command of the set function whose the mode bit being the second value;
• and
• switching the check function and the set function in response to the first value and the second value of the mode bit in the first command.