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Programming Technique to Clear a Display Area on a Low Speed Display Terminal

IP.com Disclosure Number: IPCOM000042707D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Girardi, S: AUTHOR [+2]

Abstract

Described is a programming technique to clear a display area on a low speed display terminal by a host application without impairing the response time. It applies to a class of terminals with the following characteristics: low speed communicating with a system/processor, having formatted fields protected/unprotected capabilities, having the support of a host command to erase all unprotected data on the screen, and having no screen partitioning or repeat to address order facilities. In many display-oriented applications, the screen image is organized in areas protected against operator modifications and operator work areas with protected/unprotected fields for application/operator interactions. The technique applies to applications for which only one operator work area is provided.

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Programming Technique to Clear a Display Area on a Low Speed Display Terminal

Described is a programming technique to clear a display area on a low speed display terminal by a host application without impairing the response time. It applies to a class of terminals with the following characteristics: low speed communicating with a system/processor, having formatted fields protected/unprotected capabilities, having the support of a host command to erase all unprotected data on the screen, and having no screen partitioning or repeat to address order facilities. In many display-oriented applications, the screen image is organized in areas protected against operator modifications and operator work areas with protected/unprotected fields for application/operator interactions. The technique applies to applications for which only one operator work area is provided. This area must be rectangularly shaped, and the fields defined in it must begin with an attribute character taking up a position on the screen. The drawing shows an operator work area with five fields, with P representing a "PROTECTED" attribute character and U an "UNPROTECTED" attribute character. The host application maintains a bit map of all field (attribute character) positions in the area to be cleared. The bit map is a buffer in which a bit represents a character position on the operator work area. The bit map is updated through the following steps: 1. Reset bit map (all bit off). 2. Scan output data stream for field definition, and...