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Browse Prior Art Database

Horizontal Scrolling by Pel on a CRT Display System

IP.com Disclosure Number: IPCOM000042668D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Kummer, DA: AUTHOR [+5]

Abstract

This circuit provides means to effect horizontal scrolling in a CRT display by one or more pels to provide a smooth scrolling effect. It can be used in conjunction with a system which scrolls by a character at a time to provide intermediate scrolling between character shifts. Character or graphics dot patterns are, as normal, applied in parallel to a shift register 3. The serial output stream is fed to a further shift register 4 which is clocked at the same rate as shift register 3. An output from each stage of shift register 4 is connected to an input of a multiplexer 5. In accordance with input signals applied to position inputs 0, 1 and 2, the multiplexer connects a selected one of its inputs to a video output line.

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Horizontal Scrolling by Pel on a CRT Display System

This circuit provides means to effect horizontal scrolling in a CRT display by one or more pels to provide a smooth scrolling effect. It can be used in conjunction with a system which scrolls by a character at a time to provide intermediate scrolling between character shifts. Character or graphics dot patterns are, as normal, applied in parallel to a shift register 3. The serial output stream is fed to a further shift register 4 which is clocked at the same rate as shift register 3. An output from each stage of shift register 4 is connected to an input of a multiplexer
5. In accordance with input signals applied to position inputs 0, 1 and 2, the multiplexer connects a selected one of its inputs to a video output line. Thus, the video output timing is altered by altering the multiplexer input which provides the video outputs. If single pel scrolling is required, then adjacent inputs are selected in turn. In a color system, a separate scrolling circuit will be required for each color video stream.

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