Update from below:
There is a hack to add an internal USB hub to a UMPC. Maybe this is what you are requesting.
Here is another USB Internal Hub which has a PCI bracket:
JUST COOLER UH-100 INTERNAL 4-PORT USB HUB
You would have to use a hub to connect two devices to one USB header. One 4 or 5-pin USB header = 1 USB port.
Two devices on one USB port cannot work reliably at the same time. The reason for this is (this is from memory, so it may be a little out off or missing steps):
- Once a device is plugged in, it performs a hardware handshake with the controller.
- The controller then tells the OS that a device was plugged in.
- The OS detects what the device is and loads the correct drivers.
- The driver polls the device periodically to see if there is anything to communicate and performs the transactions until the device is removed.
USB is a very host software driven interface compared to other I/O. If a second device is connected to the same wires, it could potentially cause the first device to disconnect, cause errors in the transactions, or take over the connection.
Another problem is each USB port is limited by specification to be able to supply 5V @ 0.5A max current. If two devices draw power off the port, it could trip the overcurrent sense or a resettable fuse causing the port to fault.