Browse Prior Art Database

Attribute Palette Store for a Display

IP.com Disclosure Number: IPCOM000044617D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Taylor, JL: AUTHOR

Abstract

In prior-art alphanumeric display systems attribute data is fed directly to a character generator and serializer logic to control video data. Here, the attribute data goes first to an attribute palette store which acts as a translator for emulating other display systems. The palette store may be under software control. Fig. 1 is a block diagram of a portion of a prior-art alphanumeric display system to show how attribute data (typically 8 or 16 bits) is used to control aspects of data displayed on a screen. A display buffer stores data for a full screen. Character codes together with attribute data are fed to a character generator to produce character shape data. This shape data together with the attribute data are fed to serializer logic to generate video scan data.

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Attribute Palette Store for a Display

In prior-art alphanumeric display systems attribute data is fed directly to a character generator and serializer logic to control video data. Here, the attribute data goes first to an attribute palette store which acts as a translator for emulating other display systems. The palette store may be under software control. Fig. 1 is a block diagram of a portion of a prior-art alphanumeric display system to show how attribute data (typically 8 or 16 bits) is used to control aspects of data displayed on a screen. A display buffer stores data for a full screen. Character codes together with attribute data are fed to a character generator to produce character shape data. This shape data together with the attribute data are fed to serializer logic to generate video scan data. In a typical current display, each character byte in the display buffer is matched with one, two or three bytes of attribute information. Examples of attribute bits could include: FOREGROUND RED BYTE 0 BIT 0 FOREGROUND GREEN BYTE 0 BIT 1 FOREGROUND BLUE BYTE 0 BIT 2 BACKGROUND RED BYTE 0 BIT 3 BACKGROUND GREEN BYTE 0 BIT 4 BACKGROUND BLUE BYTE 0 BIT 5 BACKGROUND OPAQUE BYTE 0 BIT 6 CHARACTER BLINK BYTE 0 BIT 7 UNDERSCORE BYTE 1 BIT 0 OVERSTRIKE BYTE 1 BIT 1 SUBSCRIPT BYTE 1 BIT 2 SUPERSCRIPT BYTE 1 BIT 3 REVERSE VIDEO BYTE 1 BIT 4 CHARACTER INVERT (VERTICAL) BYTE 1 BIT 5 CHARACTER INVERT (HORIZONTAL) BYTE 1 BIT 6 Each bit of attribute data in the display buffer is hard mapped to a particular attribute, as shown. This is w...