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Adaptation of IBM Color/Graphics Monitor Adapter to Direct Drive an Electroluminescent Display

IP.com Disclosure Number: IPCOM000061551D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Ames, RN: AUTHOR [+3]

Abstract

This article describes a method where the existing IBM color/graphics adapter card is modified to function as the required driver of the interface to the 512 x 256 pixel electroluminescent (EL) panel. EL thin film flat panel displays are replacing cathode ray tube (CRT) displays in many applications because of their flat form and equally good resolution. The need of having the IBM personal computer (PC) family interface to these displays has developed. In graphics mode it is imperative that every pixel on the display be addressed. This article describes a method where the existing color graphics adapter card is modified to function as the required driver of the interface to the 512 x 256 pixel EL panel.

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Adaptation of IBM Color/Graphics Monitor Adapter to Direct Drive an Electroluminescent Display

This article describes a method where the existing IBM color/graphics adapter card is modified to function as the required driver of the interface to the 512 x 256 pixel electroluminescent (EL) panel. EL thin film flat panel displays are replacing cathode ray tube (CRT) displays in many applications because of their flat form and equally good resolution. The need of having the IBM personal computer (PC) family interface to these displays has developed. In graphics mode it is imperative that every pixel on the display be addressed. This article describes a method where the existing color graphics adapter card is modified to function as the required driver of the interface to the 512 x 256 pixel EL panel. In addition to power and ground, the EL monitor requires the following signals: OE Video clock OE Video data OE Horizontal sync OE Vertical sync For a video clock, the PC
14.318 mhz system clock is used while any of the color outputs red, green, or blue could be used as the video data. The horizontal and vertical sync on the color card are generated by a Motorola 6845 CRT controller. Registers inside the 6845 are programmed in order to determine the timing and shape of the horizontal and vertical sync signals. The 6845's vertical total register is a 7-bit register enabling the 6845's to access up to 128 character rows. This results in the display buffer of the color graphics card to be organized into two banks of 8K bytes each in order to achieve 200 lines of video. Even numbered scan lines are displayed from the lower bank, and odd number lines from the upper bank.

Thus, in the graphics mode the displayed pixels and the display buffer are not mapped bit to bit. The number of scan lines per character row register in the 6845 is programmed to two in the graphics mode, and the RA0 (row address) of the 6845 is inserted at th...