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Browse Prior Art Database

Font Exception Tables

IP.com Disclosure Number: IPCOM000039004D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Nielsen, LR: AUTHOR

Abstract

Printers in which the characters are formed by printing selected dots of a high density dot matrix are inherently capable of printing any character set in multiple font styles of any pitch and desired print quality. A known technique for exploiting this capability is to store, in ROS (read-only storage), dot images of all desired characters in all style and pitch variations. Then font tables, which contain the ROS addresses of the images of all the characters required for a particular font, are created and stored in ROS. A particular font is activated for printing use by loading its font table from ROS to an access table in RAM (random-access memory). It is seen that in printer applications using many fonts, considerable memory capacity may be required for the ROS font tables.

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Font Exception Tables

Printers in which the characters are formed by printing selected dots of a high density dot matrix are inherently capable of printing any character set in multiple font styles of any pitch and desired print quality. A known technique for exploiting this capability is to store, in ROS (read-only storage), dot images of all desired characters in all style and pitch variations. Then font tables, which contain the ROS addresses of the images of all the characters required for a particular font, are created and stored in ROS. A particular font is activated for printing use by loading its font table from ROS to an access table in RAM (random-access memory). It is seen that in printer applications using many fonts, considerable memory capacity may be required for the ROS font tables. The present arrangement minimizes memory requirements by the use of font exception tables. The figure shows a section of ROS 10 that contains dot images of all desired characters in all desired style and pitch variations, arranged in any convenient order. The figure also shows a group of ROS font tables 11 (L1 to Ln). Each table stores the ROS 10 addresses of the dot images of all the characters for a particular font. Table L1 thus may contain the addresses for DRAFT quality dot images of all characters of a particular font. Similarly, Table L2 may contain the addresses for TEXT quality fixed pitch dot images of the same char acters; Table L3 may contain addresses for TEXT quality proportionally spaced character dot images; Table L4 may contain addresses for NEAR LETTER QUALITY fixed pitch character dot images; etc. The addresses of the character images are stored in the font tables in an ordered sequence corresponding to the character sequence of the code system being used in the machine. The figure also shows RAM font access table 12 w...