A microcomputerized interface for computer communication

In this paper an interface device for computer communication is described, based on the use of a programmable microprocessor. The aim of this Micro Front End Processor is to free the main computer from all the communication procedures management, as if some intelligence were added to the transmission line. An outline of the model, the realization of the interlocutor (the entity carrying on the colloquy) is based on, is given, the heart of the device being a software implemented Variable Structure sequential Machine. The boundaries are traced for the device toward the main computer as well as toward the transmission line, and the operation of its main components as the modem handler, the interlocutor module, and the computer handler is described. Hardwired and microprogrammed versus microcomputerized realization tradeoff is examined with respect to cost, performance, and flexibility, and the choosing criteria among the possible architectures and technological features of microcomputers are reviewed. Finally, a block diagram and a functional description of a device, based on Intel 8080 microprocessor, implementing the colloquy for the UNIVAC 1108 under EXEC 8 operating system are presented as well as an estimate of the performance of such a device.