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Character Graphics Generation

IP.com Disclosure Number: IPCOM000046311D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 52K

Publishing Venue

IBM

Related People

Peake, JW: AUTHOR

Abstract

Character graphics generation for CRT (cathode ray tube) and dot printer applications can involve Latin, ideographics and other forms of characters which may require separate character graphic generation circuits. Input character data indicates the class of character graphic being processed. In accordance with the class, one of the character generators is actuated for generating a given character graphic. The output connections of all of the character graphic output generators are dot ORed to a character buffer which then goes to the display or printing apparatus.

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Character Graphics Generation

Character graphics generation for CRT (cathode ray tube) and dot printer applications can involve Latin, ideographics and other forms of characters which may require separate character graphic generation circuits. Input character data indicates the class of character graphic being processed. In accordance with the class, one of the character generators is actuated for generating a given character graphic. The output connections of all of the character graphic output generators are dot ORed to a character buffer which then goes to the display or printing apparatus.

With each input character data or sequence of character data which are coded representations of raster patterns to be printed, a format (FMT) field selects which source of raster patterns is to be used for printing the character graphic indicated by the input character data. In addition, certain Latin parameter data, size as well as the address of the raster pattern within the respective character generators, is received. The input character data is first loaded into a prime register. The format field is used to gate a portion of the input character data to a lower portion of the prime register and activates a sequence control which is actuated by the cycle steal control signal which affects the input character data from a data storage unit (not shown). When the format indicates Latin characters, then the sequence control supplies an inhibit signal to inhibit the transfer control information from the lower portion of the prime register to later described circuits. The same signal is interpreted as an enable signal by the Latin character source. The Latin character source includes a data storage area, called a raster pattern store, which stores the physical configuration of the character graphics represented by the input character data. The input character data also goes into the Latin character source for selecting the raster pattern which then, in turn, s...