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Underscore Facility Program for a Color Display Monitor Disclosure Number: IPCOM000040376D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02

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Related People

Bertram, RL Lederer, JF Loiselle, JT [+details]


A personal computer (PC), which does not normally support the display of character underscore on a color monitor, can display underscored characters through an application program. A Basic Input Output System (BIOS) provides application access to a video controller of the PC through additional commands to the Interrupt 10 video interface. A standard 256-character font is loaded into block 0, and a second 256-character font, with each character being underscored, is loaded into block 2. A character from either of the two fonts can be selected for display. When a character is to be displayed with underscore, it is selected from the font in block 2 by the user turning on bit 3 in the attribute byte, which has all the information on how a character is to be displayed, associated with each character.