Browse Prior Art Database

Erase Count Coded Image Buffer

IP.com Disclosure Number: IPCOM000082592D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Herman, TD: AUTHOR [+2]

Abstract

This is a method for reducing buffer requirements for more efficient use of a video display output of a processor, in which terminal systems designs use concentrated processing via software control. The method is based on the fact that very seldom is data required in each character position of a line.

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Erase Count Coded Image Buffer

This is a method for reducing buffer requirements for more efficient use of a video display output of a processor, in which terminal systems designs use concentrated processing via software control. The method is based on the fact that very seldom is data required in each character position of a line.

A typical application would provide an average of 20 characters left justified on a 64-character line. The full image buffer, hardware adapter approach would contain 2O characters, followed by 44 characters of blanks which would be entirely ""painted'' by the hardware adapter.

In accordance with this method, as shown in the figures, a byte of information for each line available on a display would be stored with the number of blank characters on that line. In the event of new data being displayed on the same line, a comparison between the count coded byte for this line and the new number of blank characters is performed. Only the difference between the two counts is what has to be erased on the display line.

In the event of new data being greater than the data on the same line, the comparison will show that no erase needs to be performed (Case B). In this case, only the Erase Count Code Image Buffer needs to be updated to reflect the new number of blank characters.

The efficiency gained by this approach becomes very apparent when analyzing the overhead required by a control program, to initiate and complete a hardware character erase fu...