Single integrated circuit flash memory controller for activating external ROM sharing a common USB port

A single integrated circuit flash memory controller for activating an external ROM sharing a common USB port, comprising:

• a flash memory controller integrated circuit;
• an external ROM for storing program code;
• and
• at least one flash memory device for storing data;
• wherein the external ROM and the flash memory device are connected to the switching module of the flash memory controller integrated circuit through a same data and IP USB port, and the switching module connects to a CPU of said flash memory controller integrated circuit for enabling said flash memory controller integrated circuit to control a internal logic circuit to switch the switching module for making connection between said CPU and said external ROM so that said CPU retrieves the program code from said external ROM, and wherein when said CPU needs to retrieve data from said flash memory device, said flash memory controller integrated circuit will interrupt the connection between said CPU and said external ROM and switch to a waiting status control circuit of said CPU and thereby switching said CPU remain in a waiting mode without further retrieving program code from said external ROM, meanwhile said flash memory controller integrated circuit controls an internal logic circuit to switch said switching mode to make a connection between said flash memory device that has a buffer and a flash memory module of said flash memory controller integrated circuit to enable said CPU to retrieve data from said flash memory device through said buffer and after completing data retrieval, said internal logic circuit of said flash memory controller integrated circuit cuts off the connection between said CPU and the flash memory device and switches back to make connection between said CPU and said external ROM, and also transmits a resume signal to said CPU for continuously executing and retrieving the program code from said external ROM.