A multiple port system includes a plurality of port devices, each port device including a control register set, and a control bus coupled to the plurality of port devices. The control bus provides a control signal to each port device, and the control signal includes port address information and register address information. The control register set includes a set of registers responsive to the control signal if the port address information indicates the corresponding port device, and a designated register responsive to the control signal if the port address information indicates one of the plurality of the port devices and the register address information indicates the designated register.