ST92196A STMicroelectronics, ST92196A Datasheet - Page 116

• Manufacturer Part Number: ST92196A
• Description: 8/16-bit Mcu For Tv Applications With Up To 96k Rom, On-screen-display And 1 Or 2 Data Slicers
• Manufacturer: STMicroelectronics

OSD CONTROLLER (Cont’d)
All colors are taken from a double Palette set
(Background and Foreground) which are both OS-
DRAM mapped and thus definable in real-time.
The priority of all color layers is, from highest to
lowest:
Mouse, underline, foreground & rounding, fringe,
background and border.
Character code 00h is a test character and has no
user customized content. It is always displayed
with a border color and will appear as a “non-dis-
played character”.
8.5.3.4 Character Matrix Definition
A character is described by a matrix of dots stored
in the Font ROM memory. Two matrix sizes are
can be used to define each character pattern: ei-
ther a 9x13 matrix or a 18x26 matrix. The matrix
size can be redefined for each row Display buffer;
mixing the 2 matrix sizes on a same screen is
therefore possible.
Figure 53. Avoiding Flicker on unmagnified 18x26 characters
Original character design
with visible flicker
- ON SCREEN DISPLAY CONTROLLER (OSD)
Refer to
ROM content.
The 9x13 matrix is a compressed format where
each bit represents a 2x2 pixel dot (with no magni-
fication applied). In interlaced mode, for each dot,
2 pixels are generated on a field, the 2 others on
the other field; each row of the matrix is used for
both fields.
The 18x26 matrix is an “expanded” format where
each bit represents a 1x1 pixel dot (if no magnifi-
cation). In interlaced mode, if no magnification is
applied, each odd row of the matrix is displayed on
a field, each even row on the other field.
WARNING: As a result, when displaying the
18x26 matrix with no vertical magnification and in
interlaced mode, flicker may be visible on charac-
ters containing long single-pixel rows. To avoid
this effect, either use double pixel horizontal lines,
if possible, when designing the font (see
53). Alternatively, use the double height attribute
or choose the foreground and background colors
for reduced contrast.
Modified character design
Figure
61, for an example of the Font
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Figure