Data processing system

Claim 1

DATA PROCESSING APPARATUS COMPRISING, IN COMBINATION, A PLURALITY OF SEPARATE AND INDEPENDENT DATA PROCESSORS EACH INCLUDING PROGRAM-CONTROLLED ARITHMETIC MEANS; A GROUP OF TERMINAL EQUIPMENTS TO WHICH SAID PROCESSORS MAY REQUIRE ACCESS DURING THE EXECUTION OF PARTICULAR PROGRAMS STORED IN THE PROCESSORS; AT LEAST TWO SUB-SYSTEM CONTROL UNITS FOR CONTROLLING COMMUNICATION BETWEEN SAID GROUP OF TERMINAL EQUIPMENTS AND ALL OF SAID DATA PROCESSORS, FIRST CIRCUIT MEANS CONNECTING EACH OF SAID CONTROL UNITS TO ALL OF SAID PROCESSORS; SAID PROCESSORS INCLUDING MEANS FOR DIRECTING TO ANY SELECTED CONTROL UNIT SEIZE SIGNALS TO INITIATE COMMUNICATION WITH ANY OF SAID GROUP OF TERMINAL EQUIPMENTS; FIRST INTERLOCK MEANS FOR PREVENTING THE CONCURRENT ESTABLISHMENT OF COMMUNICATION CHANNELS FROM EITHER OF SAID CONTROL UNITS TO MORE THAN ONE OF SAID DATA PROCESSORS; SECOND CIRCUIT MEANS CONNECTED BETWEEN SAID GROUP OF TERMINAL EQUIPMENTS AND BOTH OF SAID CONTROL UNITS FOR ESTABLISHING COMMUNICATION BETWEEN ANY OF SAID TERMINAL EQUIPMENTS AND EITHER OF SAID CONTROL UNITS SO AS TO PERMIT A TRANSFER OF DATA BETWEEN THE SELECTED TERMINAL EQUIPMENT AND THE DATA PROCESSOR WHICH SEIZED THE CORRESPONDING CONTROL UNIT; SECOND INTERLOCK MEANS FORMING PART OF SAID SECOND CIRCUIT MEANS, SAID SECOND INTERLOCK MEAN INCLUDING MEANS RESPONSIVE TO SIGNALS FROM EITHER ONE OF SAID CONTROL UNITS FOR PREVENTING COMMUNICATION BETWEEN THE OTHER ONE OF SAID CONTROL UNITS AND ANY SELECTED TERMINAL EQUIPMENT OF SAID GROUP OF TERMINAL EQUIPMENTS, WHEREBY SAID ONE CONTROL UNIT CAN RESERVE AT LEAST ONE OF SAID TERMINAL EQUIPMENTS FOR SUBSEQUENT COMMUNICATION WITH THE PROCESSOR WHICH SEIZED THAT CONTROL UNIT; AND RELEASE MEANS ACTUABLE BY A SIGNAL PRODUCED IN ACCORDANCE WITH THE PROCESSOR PROGRAM, SAID RELEASE MEANS BEING OPERABLE TO DEACTIVATE SAID SECOND INTERLOCK MEANS AND THEREBY PERMIT ACCESS TO THE RESERVED TERMINAL EQUIPMENT BY SAID OTHER PROCESSORS.