THE CITY IS DIVIDED INTO FOUR QUADRANTS, EACH WITH ITS OWN RADIO FREQUENCY AND DISPATCHER. EACH ZONE IS BROKEN DOWN INTO APPROXIMATELY 25 BEATS, WHICH ARE EACH FURTHER SUBDIVIDED INTO REPORTING AREAS USED FOR STATISTICAL PURPOSES. THE THREE BURROUGHS B6700 VIRTUAL MEMORY COMPUTERS USED BY THE SHERIFF'S OFFICE INCLUDE 300 TERMINALS, OF WHICH 22 ARE DIRECTLY ASSOCIATED WITH COMPUTER-AIDED DISPATCHING (CAD). ANOTHER 18 ARE ASSOCIATED WITH DATA INPUT, BOOKING, AND OTHER CRIMINAL JUSTICE SYSTEMS. THE CAD SYSTEM IS DIVIDED INTO THE RECEIVING SECTION, DISPATCHING SECTION, REVIEW SECTION, AND ADMINISTRATIVE SECTION. THE GEOGRAPHIC BASE FILE (GBF) IS THE HEART OF THE CAD SYSTEM BECAUSE IT IS THE COMMON DENOMINATOR LINKING THE ADDRESSES OF INCIDENTS TO A BEAT WHICH IS RECOGNIZABLE IN THE SHERIFF'S DEPARTMENT. THE GBF PROVIDES TWO MAIN RESOURCES: THROUGH CAD, THE BEAT AND REPORTING AREA ARE ASSIGNED TO ALL CALLS USING THE GBF. THE BEAT IS USED IN AN OPERATIONAL CAPACITY MAINLY BY POINTING OUT THE CORRECT PATH TO FOLLOW IN RESPONDING TO A CALL. THE REPORTING AREA IS USED PRIMARILY IN THE STATISTICAL REPORTS WHICH ARE NORMALLY RUN LATER TO DIRECT THE PLANNING AND PATROL UNITS. THE IMPROVED ACCESS METHOD INTO THE GBF IS ONE WHICH UTILIZES THE BURROUGHS-DEVELOPED PACKAGE CALLED XRAM. THE THREE MODES OF ACCESS INTO THE STREET FILE WERE RETAINED: DIRECT ADDRESS, INTERSECTION, OR LANDMARK. ACCESS METHODS INTO THE GBF AND STREET FILE, AND THE FILE ORGANIZATIONS FOR EACH SECTION OF CAD (RECEIVING, DISPATCHING, REVIEW, AND ADMINISTRATIVE) ARE BRIEFLY EXPLAINED. (MHP)