Browse Prior Art Database

Displaying Overstruck Characters Using Programmed Symbols

IP.com Disclosure Number: IPCOM000062028D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

DeBry, RK: AUTHOR

Abstract

Typically, displays which refresh from a mapped regeneration buffer cannot display overstruck characters. Each character to be displayed must be predefined and stored in either a ROS (read-only storage) or RAM (random-access memory) character set generator. The display logic selects one of these predefined characters per character position on the display. This article describes a technique to generate dynamically a definition of an overstruck character, and store it in a programmed character set. When providing text function on a traditional mapped character display, the data stream is stored first in an unmapped buffer, shown here as the Text Buffer 10. This buffer contains displayable characters and control codes which operate on the data to format the screen of the Video Display 12.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Displaying Overstruck Characters Using Programmed Symbols

Typically, displays which refresh from a mapped regeneration buffer cannot display overstruck characters. Each character to be displayed must be predefined and stored in either a ROS (read-only storage) or RAM (random- access memory) character set generator. The display logic selects one of these predefined characters per character position on the display. This article describes a technique to generate dynamically a definition of an overstruck character, and store it in a programmed character set. When providing text function on a traditional mapped character display, the data stream is stored first in an unmapped buffer, shown here as the Text Buffer 10. This buffer contains displayable characters and control codes which operate on the data to format the screen of the Video Display 12. Once buffer 10 is written via line 18 by the host application, display microcode in Display Formatter 14 scans buffer 10 and, using the control codes in buffer 10, formats the Mapped Regeneration Buffer 16. This results in an image of the formatted text data on the Video Display 12. Assume that an overstruck character is to be displayed. In the data stream this appears as (CHARACTER) (BACKSPACE) (CHARACTER). For the purposes of discussion, take as an example, the overstruck character /. On the Test Data Stream line 18 this would appear as 0 (BACKSPACE) /. In this scheme, the Display Formatter 14 converts the data stream sequence into a new internal control sequence of the form: CONTROL CODE, LENGTH, PS ID, INTERNAL CODE POINT, OVERSTRIKE CHARACTER SEQUENCE The control code identifies this string of data as an overstrike sequence. The length parameter points to the end of sequence. The Programmed Symbol (PS) ID...