Browse Prior Art Database

Underscore Facility Program for a Color Display Monitor

IP.com Disclosure Number: IPCOM000040376D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bertram, RL: AUTHOR [+3]

Abstract

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.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 60% of the total text.

Page 1 of 1

Underscore Facility Program for a Color Display Monitor

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. Bit 3 is normally defined as the intensity bit in that it determines whether one of eight colors is intensified for a particular character. Bits 0-2 are used to select one of eight colors in eight lower video controller color registers. An upper eight video controller color registers have previously provided the intensified colors. Thus, when the bit 3 was on, the selected color would be intensified by being supplied from one of the upper color registers, whereas it would not be intensified if bit 3 was off and would be supplied from one of the lower color registers. Since the user of the intensity bit 3 to select th...