Summary of Efforts Expended on the Concept of 'Dynamic Update of a Microfilm File'

摘要

A description is given of the hardware developed as a feasibility prototype for a dynamically updatable microfilm information storage, retrieval, and display system. Dynamic updating is accomplished by using a magnetic strip on the microfilm in conjunction with read/write circuits. Data are stored in binary coded decimal format, 32 numerical characters of changeable information or 128 bits to each microfilm image, giving a total magnetic storage capacity of more than 300,000 bits for a 100-foot reel. A variable work length was assigned. A consecutive search capability was built to improve the retrieval response times associated with the forwardonly search technique in commercial reader/retrievers. Consecutive search is defined as the capability to store the present position or frame number location on the film reel and search in either direction (i.e. forward or reverse). Logically, first-stage comparison determines the relative location of a desired frame number with respect to present position along the length of a film reel. If the reel had just been loaded, the contents of the frame counter shift register is zero. For previous requests, the contents of the frame counter shift register will be a direct indication of present position within the film reel. Three possible logical decisions is made as a result of the firststage comparison.