Portable computer with automatic adaption to different device types on a standard port

Claim 1

A computer system, comprising: a system chassis including therein at least one central processing unit (CPU); at least one externally accessible multi-pin data connector which conforms to a mechanical and electrical specification of a standard connector format; port interface circuits connected to sense and to drive plural pins of said externally accessible data connector; a disk drive controller coupled to plural pins of said externally accessible data connector; and multiplexing logic coupled to said externally accessible data connector, said port interface circuits, and said disk drive controller; a first cable incorporating multiple data wires, and having a first multi-pin connector thereon which matches both mechanical and electrical specifications of said standard multi-pin connector format; a first external input/output device, which is physically separate from said system chassis, and which is connected to said first cable to provide bidirectional data communication using a first protocol, through said first cable and said first connector thereof and said externally accessible connector on said chassis, to and from said port interface circuits, said first external input/output device is a printer device; a second cable incorporating multiple data wires such that each of said multiple data wires is connected to a respective pin of a second multi-pin connector, said second multi-pin connector matches both mechanical and electrical specifications of said standard multi-pin connector format, except that a first pin of said second connector of said second cable, which carries a fixed voltage in the electrical specifications of said standard format, is electrically connected to a second pin of said second connector of said second cable so that said second pin also carries said fixed voltage, and the presence of said fixed voltage on said second pin is noncompliant with the electrical specifications of said standard format; a second external input/output device, which is physically separate from said system chassis, and which is connected to each of said multiple data wires of said second cable to provide bidirectional data communication using a second protocol, through said second cable and said second connector thereof and said externally accessible connector on said chassis, to and from said port interface circuits, said second external input-output device is a different device type than said printer device; and wherein said CPU includes means for querying said port interface circuits to ascertain the voltage of a second pin of said externally accessible connector on said chassis, such that said CPU can automatically switch to said first protocol when said first cable and first external device are connected to said externally accessible connector on said chassis, and can automatically switch to said second protocol when said second cable and second external device are connected to said externally accessible connector on said chassis, wherein said multiplexing logic electrically connects said externally accessible data connector and said port interface circuits when said first cable and first external device are connected to said externally accessible connector on said chassis, and said multiplexing logic electrically connects said externally accessible data connector and said disk drive controller when said second cable and second external device are connected to said externally accessible connector on said chassis.