Computer apparatus with switchable input output system

A computer apparatus, comprising:

• a main board, comprising:
• a connector;
• a management chip, coupled to the connector, and generating a first detecting signal and a second detecting signal;
• a switch, coupled to the management chip;
• and
• a first basic input output memory comprising a first basic input output system, wherein the first basic input output memory is coupled to the switch;
• and
• an external sub-board, coupled to the main board through the connector, wherein the external sub-board comprises an external input output memory and the external input output memory comprises an external input output system, wherein the first basic input output memory and the external input output memory provide different connection interfaces for different peripherals;
• wherein when the management chip detects that the external sub-board is coupled to the main board, the management chip generates the first detecting signal to cut off the switch, an enable signal enables the external input output system through the connector, and a disable signal disables the first basic input output system, and
• when the management chip detects that the external sub-board is not coupled to the main board, the management chip generates the second detecting signal to turn on the switch, the enable signal enables the first basic input output system through the switch;
• wherein detection that the external sub-board is coupled to the main board and generation of the first detecting signal to cut off the switch in response are performed automatically by the management chip, and detection that the external sub-board is not coupled to the main board and generation of the second detection signal to turn on the switch in response are performed automatically by the management chip.