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Dual Port Color Monitor Adapter

IP.com Disclosure Number: IPCOM000050051D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Kurtz, RC: AUTHOR

Abstract

Minimum additions, primarily in terms of address decodes and transceivers, are required to render a standard black and white adapter a color adapter.

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Dual Port Color Monitor Adapter

Minimum additions, primarily in terms of address decodes and transceivers, are required to render a standard black and white adapter a color adapter.

Color monitors generally require high-speed logic due to fast refresh rates. Further, their adapter circuit layout is complicated by additional logic paths to provide not only video signals but color signals.

The addition of memory to store color information requires additional memory address decode logic as well as simultaneous character, attribute, and color fetching capabilities. Furthermore, latching is necessary in the output stages in order to properly synchronize the color and video information.

Illustrated are the pertinent portions of a black and white adapter with the necessary additions for handling color. Primarily added are required color memory address decode 1, a character attribute memory, address decode 2, and tranceivers 3 and 4 on the four lowest order data lines to separate color memory data bus 5 from character/attribute memory data bus 6.

A memory cycle takes precisely half of a character's display time. One half of the character time is used to fetch the character, its attributes, and its color information. The memory output is latched in a normal manner and processed by a system processor during the other half cycle. During this second half-cycle (while the character is being processed), the processor may write to. or read from, either the character attribute o...