By applying semantic analysis to images of extended passages of text, several volumes of a chess encyclopedia have been read with high accuracy. Although carefully proofread, the books were poorly printed and posed a severe challenge to conventional page-layout analysis and character-recognition methods. An experimental page-reader system performed strictly top-down layout analysis for identification of columns, lines, words, and characters. This proceeded rapidly and reliably thanks to a recently developed skew-estimation technique. Resegmentation of broken, touching, and dirty characters was handled in an efficient and integrated manner by a heuristic search operating on isolated words. By analyzing the syntax of game descriptions and applying the rules of chess, the error rate was reduced by a factor of 30 from what was achievable through shape analysis alone. Several computer vision systems integration issues suggested by this experience are discussed.>

UNIX is a general-purpose, multi-user, interactive operating system for the Digital Equipment Corporation PDP-1 1/40 and 11/45 computers. It offers a number of features seldom found even in larger operating systems, including