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EP0153197A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

A method of operating a display system

Assignee: International Business Machines Corp
•
Filing: 1985-02-21
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Granted: —
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Expires: 2005-02-21
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Abstract

Abstract By selecting the starting time of the display readout in raster-fashion of a pel buffer (16), the pel data is mapped to a display screen (10) with an arbitrary displacement with respect to the screen for relocation or scrolling of the pel image on the screen. To compensate for non-congruency between the pel data window and the screen viewport definitions and to provide scrolling on a pel basis, the positioning of the window on the screen includes fine adjustment achieved by a determinable delay between the scanning of the buffer and the generation of the screen raster. The display circuits include means to extend the window background to fill in gaps between the edges of a window of pel data chosen to be displayed and a larger screen viewport in which it is to be displayed. System read/write access times to the buffer are interleaved with and synchronized to the data fetch times of the display.

Inventors

  • 👤 Dean Alan Stockwell

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-07 08:10
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/40; G09G5/14

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 156 words
A method of operating a display system for displaying a window (I) of data from a pel buffer (16) in a viewport (V) on a display screen (10), wherein the display system includes first means (74) defining the window with respect to the buffer and second means (24) defining the viewport with respect to the screen, characterised in that the first and second means operate on different radices, and in that the method comprises choosing a viewport at least as large as the window of data to be displayed, scanning the buffer and the screen at integrally related pel rates, modifying the buffer addressing to bring the window of data approximately into desired registration with the viewport subject to the constraints imposed by the said different radices, and providing a variable delay in the application of the pel data from the buffer to the screen to bring the window exactly into desired registration with the viewport.
Claim 2
Independent Claim 156 words
A method of operating a display system for displaying a window (I) of data from a pel buffer (16) in a viewport (V) on a display screen (10), wherein the display system includes first means (74) defining the window with respect to the buffer and second means (24) defining the viewport with respect to the screen, characterised in that the first and second means operate on different radices, and in that the method comprises choosing a viewport at least as large as the window of data to be displayed, scanning the buffer and the screen at integrally related pel rates, modifying the buffer addressing to bring the window of data approximately into desired registration with the viewport subject to the constraints imposed by the said different radices, and providing a variable delay in the application of the pel data from the buffer to the screen to bring the window exactly into desired registration with the viewport.
Claim 3
Dependent Claim 33 words
The method of claim 2, additionally including the step of filling in a gap between the window and a boundary of the viewport with an extension of the pel background of the window.
Claim 4
Dependent Claim 54 words
The method of claim 1 or 2, additionally including the steps of providing access times to update the buffer interleaved with fetching of data from the buffer in the scanning of the window therein, the access times being synchronized to the scanning to accommodate differences in the timing of the access and fetching operations.

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