``Intergraphic,'' A Microprogrammed Graphical-Interface Computer

Abstract

The paper describes a proposed microprogrammed interface computer, ``Intergraphic,'' which will link many (initially 13; potentially more than 50) general-purpose graphical terminals to a central processor. Intergraphic will generate new images once only, at high speed (10-MHz incremental plotting rates) on one of several small, electrostatically deflected, precision CRT's. The images will be generated on a 1024 by 1024 grid in incremental and random-point display modes by fast microcode sequences which interpret display lists from the central processor. The centrally generated images will be scan converted to standard television video signals and recorded on a multitrack video disk(s), each track refreshing a low-cost standard television terminal. User feedback will be via raster coordinates, determined by a light-pen (``raster-pen'') and simple counting circuits at each terminal. The paper concentrates on the digital interface structure which is versatile and fast (3-5 ns integrated circuits and 100-ns cycle-time READ-only memory). The description centers on display generation, although the structure is largely general purpose. The proposed operating system is outlined only since it is in an early stage of development. Also, the order-code accompanying data from the central processor is incomplete. However, new orders can be readily interpreted by adding microprograms to the READ-only memory (i.e., ``firmware,'' not hardware extensions); thus, the interface will also be a useful medium for experimentation in graphical structures and communication.