Browse Prior Art Database

Reverse Video Attribute Handler for Video Display Terminals

IP.com Disclosure Number: IPCOM000100171D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Wolgin, NB: AUTHOR

Abstract

Disclosed is a circuit that automatically reduces the brightness of reverse video characters as displayed on a video display terminal (VDT).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 83% of the total text.

Reverse Video Attribute Handler for Video Display Terminals

       Disclosed is a circuit that automatically reduces the
brightness of reverse video characters as displayed on a video
display terminal (VDT).

      Most VDTs are designed to allow highlighting of characters on
the screen.  Application programmers use highlighting to draw
attention to a given part of a screen. In a color VDT, the programmer
will use a vibrant color, such as red, to draw the attention of the
operator to a specific field or character on the screen.  In a
monochrome VDT the choices are more limited.  Many inexpensive VDTs
have only 2 bits of information available per pel or dot. The dot may
be off, on or highlighted (high intensity).  To add more options,
these choices are also often available as reverse video (black on
white, etc.) as well. Typically, the attributes are programmable on a
field, line or character basis.  However, when a reverse video
character appears next to a normal video character, the reverse video
character often is perceived as too bright.  This is also true for
high-intensity normal and reverse characters.

      The drawing shows a circuit that accepts the reverse video
attribute from the character generator logic and reduces the
brightness of the reverse video characters on a
character-by-character basis.

      The reverse video attribute signal is used to select a
reference zener diode with a lower voltage than normal, resulting in
the gain of t...