Browse Prior Art Database

Direct Extraction of Data From the Refresh Buffer of a Display

IP.com Disclosure Number: IPCOM000047125D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07

Publishing Venue

IBM

Related People

Authors:
Barnett, CJ Dyche, MP Mullery, C Ng, YH [+details]

Abstract

This article describes a technique for extracting any single row of displayed data under the command of a microprocessor or similar system. The data is then available for use by the microprocessor. One application for this process is when an audio output is required from the display terminal. When a row of display data is required by a microprocessor, it has to extract the data from the refresh buffer of the display. In this application there is no simple direct access path to the data store. The data must be obtained from the display as it is sent to the screen for refresh. Due to the fast scan rate of a refresh-type display, most microprocessors cannot issue I/O read commands fast enough to extract data from the refresh data stream as it is refreshed.