GM5020 Datasheet, PDF (67/86 Pages) List of Unclassifed Manufacturers – Graphics Processing IC providing high-quality images for LCD monitors and other pixelated displays

Genesis Microchip
gm5020 / gm5020-H Data Sheet
code “00” is mapped to the background color using the window region background color or using
foreground color 2.
Frame Buffer Resident Fonts
External frame buffer resident character font tables are supported. The frame buffer interface
supplies addresses to fetch character font scan lines via the frame buffer interface port.
The frame buffer based font table supports characters with programmable pixel map organization
up to a maximum size of 16 pixels horizontally by 24 pixels vertically. The horizontal character
width must be an even number of pixels.
When an external frame buffer is used to store fonts, each character row in the OSD may be
programmed to index into one of four user defined font tables. This provides up to 1024
characters in a single character mapped OSD image and is intended to allow multi-language OSD
support.
Frame buffer based fonts support up to three foreground colors per character and one background
color per character, similar to using two bits per pixel mode using SRAM resident fonts as
described above.
4.15.1.3. Background Color of Characters
There are two modes of programming the background color of characters within an OSD image.
The OSD controller may be programmed such that it is in Background Windows Mode. This
mode of operation allows up to four user programmable background windows to be displayed
simultaneously. Each background window has a color attribute, in addition to column and row
start and stop parameters. Background Windows Mode enables OSD images to be quickly
designed with little programming.
With Background Windows Mode disabled, the background color of characters may be
programmed such that each character has a unique background color.
Background Windows Mode Enabled
Up to four background windows are supported. The windows control the background color.
Windows may overlap and have a priority sequence. Window sizes are programmable and are
defined by host registers. Transparency is achieved by setting the background color for a window
to “00”.
Background Windows Mode Disabled
When background windows are disabled, the background color for each character in the OSD
image is user-programmable. In one bit per pixel mode each character has one foreground and
one background color defined. In two bit per pixel mode each character has three foreground
colors defined, and the background color is the same as foreground color 2.
4.15.1.4. Character Blinking
Character blinking is enabled by setting bit 8 of the character attribute. A global host parameter
is set to then make the desired characters blink. Blink frequency and duty cycle is programmable
through host registers. When a character is blinking, foreground colors periodically revert to the
background color of the character. Blinking frequency is proportional to the display frame rate.
February 2002
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C5020-DAT-01Q