Browse Prior Art Database

Dot Insert Logic for Graphic Characters

IP.com Disclosure Number: IPCOM000050254D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Dean, ME: AUTHOR [+4]

Abstract

This article relates to a method and apparatus for utilizing an 8-bit wide character generator read-only storage (ROS) module to generate a special 9-bit wide line graphic symbol for a display attachment. All the characters (alphanumeric and line graphic) are assigned an 8-bit character code which corresponds to a block address in the character generator, as shown in Fig. 1. The character generator contains the dot patterns to be displayed on a raster scan cathode ray tube screen. Note that all of the line graphic characters are contained together in one block of the character generator.

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Dot Insert Logic for Graphic Characters

This article relates to a method and apparatus for utilizing an 8-bit wide character generator read-only storage (ROS) module to generate a special 9-bit wide line graphic symbol for a display attachment. All the characters (alphanumeric and line graphic) are assigned an 8-bit character code which corresponds to a block address in the character generator, as shown in Fig. 1. The character generator contains the dot patterns to be displayed on a raster scan cathode ray tube screen. Note that all of the line graphic characters are contained together in one block of the character generator.

The logic shown in Fig. 2 is to be utilized in a display having a 9-dot wide character space. For alphanumeric character codes, 7 dots are used for the character and 2 dots are used for spacing between adjacent characters. For the line graphic characters, a continuous horizontal line of dots would be desirable whereby no spacing exists between adjacent characters. However, this normally is not done considering the 8-bit wide code and 9-bit wide character length. For the case of the graphic characters, if the least significant bit in the character generator (bit 1), as shown in Fig. 2, is a logic 1, then a 9th dot of the character must also be a logic 1. Otherwise, the 9th dot will be a logic zero.

Generally, the output of the character generator is loaded in parallel into a shift register and clocked out serially each dot time. By using a p...