Browse Prior Art Database

Method of Propagating Attribute Information for Displays

IP.com Disclosure Number: IPCOM000047218D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Csurics, L: AUTHOR [+4]

Abstract

When a data stream is processed for a formatted display it is necessary to propagate the attribute information throughout fields on the display. This entails propagation from one character to the next and from one row to the next. The current methods of achieving this either involve a hardware buffer scan in conjunction with writing the display or a software buffer scan prior to writing the display. This method makes use of a hardware scan from character to character with hardware feedback at the end of each row and is best suited to devices where the rows are updated individually under software control. At the start of processing a data stream for display, a list containing assumed starting attributes for each row on the display is initialized so that the attribute for the first row is non-display.

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Method of Propagating Attribute Information for Displays

When a data stream is processed for a formatted display it is necessary to propagate the attribute information throughout fields on the display. This entails propagation from one character to the next and from one row to the next. The current methods of achieving this either involve a hardware buffer scan in conjunction with writing the display or a software buffer scan prior to writing the display. This method makes use of a hardware scan from character to character with hardware feedback at the end of each row and is best suited to devices where the rows are updated individually under software control. At the start of processing a data stream for display, a list containing assumed starting attributes for each row on the display is initialized so that the attribute for the first row is non-display.

This prevents inadvertent display of protected data. At the end of the data stream the rows are written starting with the first row.

The hardware saves the last encountered attributes for the row and returns them to the software. The returned attributes are then used to replace the starting attributes for the next row, and so on. When the end of the attribute list is reached, the returned attributes are compared with the starting attributes for the first row. If there is a difference, the first row is rewritten and the list reprocessed.

The following high level design language statements illustrate a typical sof...