a microprogrammable data communications preprocessor exercises detailed control over a multiplicity of data lines communicating with a microprogrammable central processor while requiring central processor attention on a message basis only . further minimization of central processor intervention is achieved through a direct memory access channel which permits data transfer directly from the preprocessor to the main memory of the central processor . the preprocessor also includes a line adapter associated with each data communications line for interface purposes , a scratch pad memory for storing data line parameters , and a microprogrammable serial byte microprocessor . operational speed is enhanced through the inclusion of automatic operation logic which effectively by - passes the serial byte microprocessor for an automatic transfer of two bytes of data .