Black Box Explains...Advanced printer switches..
Matrix—A matrix switch is a switch with a keypad for selecting one of many input ports to connect to any one of many output ports.
Port-Contention—A port-contention switch is an automatic electronic switch that can be serial or parallel. It has multiple input ports but only one output port. The switch monitors all ports simultaneously. When a port receives data, it prints and all the other ports have to wait.
Scanning—A scanning switch is like a port-contention switch, but it scans ports one at a time to find one thats sending data.
Code-Operated—Code-operated switches receive a code (data string) from a PC or terminal to select a port.
Matrix Code-Operated—This matrix version of the code-operated switch can be an any-port to any-port switch. This means than any port on the switch can attach to any other port or any two or more ports can make a simultaneous link and transfer data.