THE DEPARTMENT'S GEOGRAPHIC BASE FILE (GBF) HAD ITS ORIGINS IN THE COLLECTION OF GEOGRAPHIC DATA FOR YEAR-TO-YEAR COMPARISONS OF ACTIVITY IN BROAD GEOGRAPHIC AREAS. IN 1967, A FULL STUDY OF PATROL PERSONNEL ASSIGNMENTS PROMPTED RECOMMENDATIONS FOR A TOTALLY NEW PATROL BEAT PLAN AND THE DEVELOPMENT OF A COMPUTERIZED GBF. THE FILE PROCESSING WAS BROKEN DOWN INTO THREE ROUTINES: A ROUTINE TO CONVERT ALL ADDRESS INFORMATION INTO A CODED FORMAT FOR INPUT TO THE ACTUAL GBF ROUTINE AND FOR LATE FILE STORAGE, THE GBF ROUTINE TO CORRELATE THE ADDRESS CODE TO THE PROPER SECTOR, AND A THIRD ROUTINE TO MATCH THE SECTOR TO THE PROPER BEAT NUMBER FOR THE WORK SHIFT OF THE REPORTED ACTIVITY. THE SYSTEM SERVES ADMINISTRATIVE, OPERATIONAL, AND PLANNING PURPOSES. IT ALSO SERVES THE IDENTIFIABLE FUTURE NEEDS AS WELL AS CURRENT NEEDS, HAS THE FLEXIBILITY TO ACCOMODATE CHANGES IN POPULATION MIX, HOUSING PATTERNS, CRIME TRENDS, SERVICE DEMANDS, AND COMMUNITY PRIORITIES. THE THREE PRIMARY DATA CATEGORIES PROCESSED THROUGH DAYTON'S SYSTEM ARE DISPATCHES (CALLS-FOR-SERVICE), CRIMES, AND ARRESTS. A WIDE VARIETY OF STATISTICAL AND DETAILED REPORTS, ALONG WITH STATISTICAL MAPS AND SHADE MAPS ARE AVAILABLE TO USERS. ALL DATA APPLICATIONS WERE DEVELOPED FOR AND ARE RUNNING ON AN NCR CENTURY COMPUTER. THE PROGRAMS WERE ORIGINALLY WRITTEN IN NCR'S NEAT/3 LANGUAGE, ALTHOUGH SOME ROUTINES ARE BEING CONVERTED TO COBOL. FURTHER TECHNICAL INFORMATION IS PROVIDED REGARDING THE GBF OPERATIONAL DESIGN, SYSTEM CODES, AND ACCESS AND ENTRY METHODS. (MHP)