EPISC (ETL's pattern information computing systems) is a computer system developed at ETL(Electrotechnical Laboratory) for pattern information research in the national project PIPS (Pattern Information Processing System) inaugurated in 1971, and is intended to be an original guide of PIPS Prototype the target of the Project. It has been implemented toward an in-house computer network, and is a star structured computer complex in which main and sub-computers communicate through high speed channels. For computer communication in EPICS, two levels of protocol are provided. Low level protocol is carried out by a newly developed hardware Computer Communication Controller and a resident module controlling it. High level protocol provides system services for an interface between user processes and EPICS control system. Those functions include remote job entry, file control and processes synchronization and are carried out by a non-resident module. Described are what kinds of high level protocol are well used for computer communication and that protocol sequences are reduced to five simple patterns observed as everyday occurrences in EPICS. Usage patterns of high level protocol sequences depend on experiment environments among work groups rather than on their research field.