US5574478A
Expired / Lapsed
US
⏱️ 0.0 years remaining
VGA color system for personal computers
Assignee: Cirrus Logic Inc
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Filing: 1992-04-27
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Granted: 1996-11-12
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Expires: 2012-04-27
Abstract
Abstract Modifications to a prior art system known as video graphics adapter (VGA) for displaying color images on a monitor attached to a personal computer. The modifications provide the following four enhancements to a standard VGA system: (i) user definable border color; (ii) automatic powering down of the digital analog converter (DAC) component of the VGA RAMDAC and monitor sense comparator for LCD monitors when the RAMDAC is not in use; (iii) stopping of the RAMDAC clock for LCD monitors when the RAMDAC is not in use; and (iv) true color support.
Inventors
- 👤 Vlad Bril
- 👤 Boyd G. Pett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 08:58
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/02; G09G5/06; G09G5/024; G09G5/36; G09G5/39; G09G5/395
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
147 words
In a personal computer having a color monitor and using a video graphics adapter to place color images from a video RAM on the monitor, said video graphics adapter having a RAMDAC including a RAM array and a digital to analog converter coupled between said RAM array and said monitor, said digital-analog converter adapted to convert a digital signal representing red, blue and green from said RAM array to an analog RGB signal used by the monitor to create a color display, the improvement comprising: a) a border color register coupled to the digital-analog converter of the video graphics adapter, said border color register for storing user selected red, blue and green colors; b) means for selecting one of said video RAM and said border color register as a source of color data for each pixel to be displayed on the monitor by the video graphics adapter.
Claim 2
Dependent Claim
147 words
In a personal computer having a color monitor and using a video graphics adapter to place color images from a video RAM on the monitor, said video graphics adapter having a RAMDAC including a RAM array and a digital to analog converter coupled between said RAM array and said monitor, said digital-analog converter adapted to convert a digital signal representing red, blue and green from said RAM array to an analog RGB signal used by the monitor to create a color display, the improvement comprising: a) a border color register coupled to the digital-analog converter of the video graphics adapter, said border color register for storing user selected red, blue and green colors; b) means for selecting one of said video RAM and said border color register as a source of color data for each pixel to be displayed on the monitor by the video graphics adapter.
Claim 3
Dependent Claim
37 words
The improvement defined by claim 1 wherein each of said red, blue and green colors is represented by a 6 bit value and said border color register is loaded by three writes to said border color register.
Claim 4
Dependent Claim
35 words
The improvement defined by claim 1 wherein said selecting means is a multiplexor having said digital-analog converter coupled to its output and having said border color register and said RAM array coupled to its input.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-11-12 | 2000-05-13 | 2000-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-12 | 2004-05-13 | 2004-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-12 | 2008-05-13 | 2008-11-12 | $7700.00 | Window Closed / Lapsed |