Convergent Technologies, Inc.

Richard W Lowenthal

Michael Ramsay

Stephen C Seike

Drew S Hoffman

Larke E Reeber

Gregory V Walsh

A page mode memory controller for a multi-plane color video display providing three bits/pixel corresponding to three page partitioning in each of sixteen 64K dynamic RAMs is described. The three bits/pixel are routed to a color lookup table to provide a choice of eight colors from a palette of 64 colors. Graphic display information is combined with alphanumeric video information on a pixel-by-pixel basis. The combined graphic/alphanumeric information is then converted from a digital signal to an analog signal. Page mode reads access three color planes for video display cycles using a counter for the two least significant memory column address bits. To create the displayed image, vectors are drawn three times, once at each plane.

Multi-plane page mode video memory controller

A method and apparatus is disclosed for allowing simultaneous depression or chording of a multiple number of keys on a keyboard coupled through an interface circuit to a computer operating system. An arbitrary association can be made to the chord which is distinct from the association made with its component keys. A dedicated processor system in the keyboard peripheral scans and stores in a dedicated memory the identity of all keys detected in the depressed state during the scan of the keyboard. For transmission to the computer operating system, each key depression detected during the scan is represented as an 8-bit binary component and the most significant bit of each binary component is set to the same one of the two permissible binary values, except for the most significant bit of the binary component representing the last depressed key detected during the scan of the keyboard. The most significant bit of that component is set to other of the two permissible binary values.

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Los Gatos, CA, United States of America

Richard W Lowenthal