Special Purpose Communication Devices
A central site intelligent controller is connected directly to a single port on the front end processor and can handle up to 32 outgoing lines (reduces the processing of the FEP, increases the number of lines available)
Controllers were originally designed terminals not microcomputers in mind ==> overload problems
To multiplex means to place two or more simultaneous transmissions on a single communication circuit
Multiplexing telephone calls = several simultaneous voice calls on one circuit
Multiplexing a data communications network means that several simultaneous data transmissions are sent over one circuit