Conversational Access to a 2 0 4 8

LAP6 is an on-line system running on a 2048-word LINC which provides full facilities for text editing, automatic filing and file maintenance, and program preparation and assembly. It focuses on the preparation and editing of continuously displayed 23,040-character text strings (manuscripts) which can be positioned anywhere by the user and edited by simply adding and deleting lines as though working directly on an elastic scroll. Other features are available through a uniform command set which itself can be augmented by the user. The machine, although small, aids program design by providing display scope and premarked randomly addressable LINC tapes as standard items, in an environment similar to that of a sophisticated terminal. The tapes are logically similar to a disk. Priority was given to the design of efficient tape algorithms to minimize the limitations of the small memory. Techniques developed for handling scroll editing, filing, and the layered system structure are outlined. LAP6 is used by about 2000 people in 11 countries. Its design was strongly influenced by performance criteria established in interviews held with the LINC users themselves during the specification period.