Browse Prior Art Database

Display Definition Control for Graphics Displays

IP.com Disclosure Number: IPCOM000060892D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Rackley, DP: AUTHOR [+2]

Abstract

A technique is described whereby graphic displays are enhanced so as to increase the number of vertical resolution modes of the display while not altering the horizontal sweep rate capabilities of the display. The technique described herein extends the concept of programmable resolution to not only support the compatibility of 480 and 400 lines of vertical resolution, but provides for Main Frame Interactive (MFI) requirements of 500 to 540 lines, as well as 350 lines for Enhanced Graphics Adapter (EGA) type of software requirements. The concept also provides the capability to handle other resolutions or aspect ratios, such as high definition television media. The essence of the concept is that it makes the Vertical Display Enable (VDE) signal available to the display.

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Display Definition Control for Graphics Displays

A technique is described whereby graphic displays are enhanced so as to increase the number of vertical resolution modes of the display while not altering the horizontal sweep rate capabilities of the display. The technique described herein extends the concept of programmable resolution to not only support the compatibility of 480 and 400 lines of vertical resolution, but provides for Main Frame Interactive (MFI) requirements of 500 to 540 lines, as well as 350 lines for Enhanced Graphics Adapter (EGA) type of software requirements. The concept also provides the capability to handle other resolutions or aspect ratios, such as high definition television media. The essence of the concept is that it makes the Vertical Display Enable (VDE) signal available to the display. The VDE signal pulse has a width equal to the number of horizontal sync pulses corresponding to the number of scan lines which fills the data area. Fig. 1 shows the typical pulse width for a 350-line VDE and a 480-line VDE. The V Sync and the VDE signals are then ORed together, as shown in Fig. 2, to reduce the number of signal lines on the interconnect cable. The width of the VDE pulse is measured by the display and converted to a resistance value. Atypical implementation is shown in Fig. 3. Resistors R are used to control the gain of the display's vertical drive circuit in the same way that the vertical size potentiometer does on a conventional disp...