Front-End Processor
A front-end processor (FEP) is generally a computer or processing unit that produces and manipulates data before another computer or processor receives it. (A processor is generally a shortened name for a microprocessor or a central processing unit (CPU).) FEPs are so called because they go between the communications lines (that sometimes directly connect into the processor) and the processor itself. The front-end processor is sometimes synonymous with a communications controller (an intermediary device used in transferring communications to and from the host ("main") computer to which it is connected), though the latter is usually not as flexible in its functions as that of an FEP.
Front-end processors were invented to reduce routine teleprocessing functions on processors within mainframe computers. Later FEPs were designed to be inexpensive to install and maintain in order to reduce using the higher priced CPUs. Front-end processors were engineered to provide the common functions needed to attach terminals, printers and other devices to computer systems through communication lines. They typically attach to the computer through channel interfaces and communication circuits via Line Interface Cards. FEPs are usually used to relieve the processor of such routine tasks as transmitting, receiving, and encoding messages; assembling and disassembling groups of data ("packets"); detecting, correcting, and controlling errors, and managing the lines running to and from other devices.
For example, International Business Machines (IBM) used FEPs as specialized hardware platforms in order to relieve the simple communications functions for their mainframe computers. Over the years the computer industry has adopted them as a primary method for communication to various computer systems (from mainframe to microcomputer systems). The software that controls the FEP and defines what exactly is attached to the FEP is the Network Control Program (NCP). The NCP is created and customized for each computer system and loaded into the FEP. The customizations of the NCP for a particular configuration of communication lines and attached devices entail a very detailed process and require the talent of a highly specialized computer programmer.
FEPs have developed into new functions since their inception. They now perform many "backbone networking" functions such as routing, transporting, and networking of the Systems Network Architecture (SNA). (A backbone is a communication network of transmissions over the Internet that carries major traffic between smaller networks.) Many information technology (IT) companies implement multiple FEPs with such features to enable wider support of their SNA or backbone network. The FEPs also perform a service known as boundary function that includes such services as converting network addresses to local addresses and polling of remote devices.
This is the complete article, containing 424 words
(approx. 1 page at 300 words per page).
