A CD-ROM control chip is provided for a use of firmware information update in the CD-ROM system. The control chip at least includes a microprocessor, a decoder, a controller, and an extra memory. The microprocessor is coupled to a data bus, and further coupled to an external ROM, which stores all firmware information. The decoder is coupled to the microprocessor through the data bus, and is also coupled to an external buffer memory and an external main board interface. The external main board interface allows the CD-ROM control chip to communicate with an external computer. The controller is coupled to the decoder, and is coupled to the microprocessor the data bus. The controller is used to receive information and control signals from an external CD. The extra memory is coupled to the microprocessor through the data bus. When the microprocessor starts to update the firmware information, it generates at least one output enabling signal, one chip selecting signal, and one writing-in signal, and sends these signals to the external ROM. The external ROM is treated as an information storing space, and the extra memory is treated as execution space used by an update program routine.