Abstract: A data transfer network uses an I/O subsystem to support a main host computer in managing data transfers to and from remote data terminals. The I/O subsystem may constitute one or more units called a Line Support Processor. The Line Support Processor uses internal processor means to control a plurality of line adapters each of which has a data-comm line to a data set or data terminal. Control operations by said internal processor permit selected line adapters to operate selected types of protocols using synchronous or asynchronous transmission. Data communication information and commands in high level language data are loaded into auxiliary memories in the internal processor means and into each line adapter where the internal processor means acts to convert this language data into usable protocols.

Abstract: An I/O subsystem, controlled by a microprocessor, includes a plurality of line adapters, each of which provides data-comm lines to remote terminal units. Each line adapter has a USART control unit and a timer unit having internal registers which can be written-into or read-out from by said microprocessor which uses means to select a particular line adapter to access a particular register in the USART unit or the timer unit.

Abstract: Data transfers between remote data sets, data terminals and a main host computer are controlled by a peripheral-controller designated as a Line Support Processor (LSP). The LSP manages a plurality of line adapters, each of which handles a separate data comm line. The LSP includes internal processor means and interface circuit means to effectuate data transfer operations using a variety of protocols and systems both for bit-oriented and byte-oriented data transfers.

Abstract: In a data communications system where a plurality of line adapters connect to remote peripheral units there is provided a control system for controlling selected Automatic Calling Units which can dial connection lines to remote peripherals or systems. A microprocessor having output control registers can select specific line adapters having an ACU-output register. It can then load dialing-digit data and ON/OFF control data into the ACU-output register for controlling the associated Automatic Calling Unit.