A METHOD FOR ESTABLISHING A DIRECT BRANCH COMMUNICATION FROM AN OBJECT PROGRAM TO A SUBROUTINE OF THE MASTER CONTROL PROGRAM INCLUDES ADDRESS WORDS IDENTIFYING TER CONTROL PROGRAM INCLUDES ADDRESS WORDS IDENTIFYING THE LOCATIONS IN MEMORY OF THE SUBROUTINES TO WHICH A DIRECT BRANCH COMMUNICATION IS DESIRED. EACH ADDRESS WORD INCLUDES A UNIQUE FLAG DIGIT. WHEN AN OBJECT PROGRAM ATTEMPTS TO ESTABLISH A BRANCH COMMUNICATION TO A SUBROUTINE IN THE MASTER CONTROL PROGRAM BY FETCHING ONE OF THE ADDRESS WORDS, THE COMMUNICATION IS IN FACT ONLY ESTABLISHED IF THE FETCHED WORD CONTAINS THE FLAG DIGIT. THE SAME STEPS INITIATE THE EXECUTION OF A TEST ROUTINE EITHER IN THE EVENT THE INFORMATION CALLED BY THE OBJECT PROGRAM DOES NOT CONTAIN THE FLAG DIGIT OR IN THE EVENT A HARDWARE INTERRUPTION TAKES PLACE. APPARATUS FOR ESTABLISHING THE DIRECT BRANCH COMMUNICATION INCLUDES A FIRST REGISTER FOR STORING COMPUTER INSTRUCTIONS, A SECOND REGISTER FOR STORING A MEMORY ADDRESS, AND A THIRD REGISTER FOR STORING INFORMATION TO BE EXCHANGED WITH THE LOCATION IN THE COMPUTER MEMORY IDENTIFIED BY THE ADDRESS STORED IN THE SECOND REGISTER. RESPONSIVE TO THE STORAGE OF A BRANCH COMMUNICATION INSTRUCTION IN THE FIRST REGISTER, A GATE TRANSFERS A SELECTED ADDRESS WORD IDENTIFYING THE LOCATION IN THE MEMORY OF A SUBROUTINE FROM THE MEMORY TO THE THIRD REGISTER. A CHECK CIRCUIT INSPECTS THE SELECTED ADDRESS WORD TO DETERMINE IF A FLAG DIGIT IS PRESENT. RESPONSIVE TO THE PRESENCE OF THE FLAG DIGIT, A GATE TRANSFERS THE SELECTED ADDRESS WORD TO THE SECOND REGISTER TO INITIATE EXECUTION OF THE CORRESPONDING SUBROUTINE.