MEMORY BUS CHECKING PROCEDURE
A method for checking usable width of a data bus linking a host device and a memory card. Preferably, at the boot up process the host device sends a test bit pattern to the memory card through the data bus (Step 210). The test bit pattern can be (1010...) or (0101...). Upon receiving the test bit pattern (Step 210), the memory card sends a response bit pattern to the host device through the same data bus (Step 230). The response bit pattern is complement to the test bit pattern so as to allow the host device to compare the response bit pattern with the test bit pattern (Step 240), and determines the usable width of the data bused based on the comparison result (Step 250).