Simultaneous Flat Panel / CRT Display
The 65540 / 545 provides simultaneous display
operation with Multi-Sync variable frequency or
PS/2 fixed frequency CRT monitors and single
panel-single drive LCDs (LCD-SS), dual panel-dual
drive LCDs (LCD-DD), and plasma and EL panels
(which employ single panel-single drive interfaces).
Single drive panels sequence data in the same
manner as CRTs, so the 65540 / 545 provides
simultaneous CRT display with LCD-SS, Plasma,
and EL panels by driving the panels with CRT
timing. LCD-DD panels require video data alter-
nating between two separate locations in memory.
In addition, a dual drive panel requires data from
both locations simultaneously. A framestore area,
also called the frame buffer, is required to achieve
this operation. The 65540 / 545 innovative archi-
tecture implements the frame buffer in an unused
area of display memory, reducing chip count and
subsystem cost. As an option, an extra 16-bit wide
DRAM can be used as an external frame buffer,
improving performance while in simultaneous flat
panel/CRT modes. The 65540 / 545 provides
simultaneous display with monochrome and color
LCD-DD panels with a single 256Kx16 DRAM.
DISPLAY ENHANCEMENT FEATURES
Display quality is one of the most important
features for the success of any flat panel-based
system. The 65540 / 545 provides many features to
enhance the flat panel display quality.
"TRUE-GRAY" Gray Scale Algorithm
A proprietary polynomial-based Frame Rate
Control (FRC) and dithering algorithm in the 65540
/ 545's hardware generates a maximum of 61 gray
levels on monochrome panels. The FRC technique
simulates a maximum of 16 gray levels on
monochrome panels by turning the pixels on and off
over several frames in time. The dithering
technique increases the number of gray scales from
16 to 61 by altering the pattern of gray scales in
adjacent pixels. The persistence (response time)
of the pixels varies among panel manufacturers and
models. By re-programming the polynomial (an 8-
bit value in Extension Register XR6E) while
viewing the display, the FRC algorithm can be
adjusted to match the persistence of the particular
panel without increasing the panel's vertical refresh
rate. With this technique, the 65540 / 545 produces
up to 61 flicker-free gray scales on the latest fast
response "mouse quick" film-compensated mo-
nochrome STN LCDs. The alternate method of
reducing flicker -- increasing the panel's vertical
refresh rate -- has several drawbacks. As the
vertical refresh rate increases, panel power
consumption increases, ghosting (cross-talk)
increases, and contrast decreases. CHIPS'
polynomial FRC gray scale algorithm reduces
flicker without increasing the vertical refresh rate.
RGB Color To Gray Scale Reduction
The 24 bits of color palette data from the VGA
standard color lookup table (CLUT) are reduced to
6 bits for 64 gray scales via one of three selectable
RGB color to gray scale reduction techniques:
1) NTSC Weighting: 5/16 Red 9/16 Green 2/16 Blue
2) Equal Weighting: 5/16 Red 6/16 Green 5/16 Blue
3) Green Only: 6 bits of Green only
NTSC is the most common weighting, which is
used in television broadcasting. Equal weighting
increases the weighting for Blue, which is useful for
Applications such as Microsoft Windows 3.1 which
often uses Blue for background colors. Green-Only
is useful for replicating on a flat panel the display of
software optimized for IBM's monochrome
monitors which use the six green bits of palette
data.
SmartMap™
SmartMap™ is a proprietary feature that can be
invoked to intelligently map colors to gray levels in
text mode. SmartMap™ improves the legibility of
flat panel displays by solving a common problem:
Most application programs are optimized for color
CRT monitors using multiple colors. For example,
a word processor might use a blue background with
white characters for normal text, underlined text
could be displayed in green, italicized text in
yellow, and so on. This variety of colors, which is
quite distinct on a color CRT monitor, can be
illegible on a monochrome flat panel display if the
colors are mapped to adjacent gray scale values. In
the example, underlined and italicized text would be
illegible if yellow is mapped to gray scale 4, green
to gray scale 6 with the blue background mapped to
gray scale 5.
SmartMap™ compares and adjusts foreground and
background grayscale values to produce adequate
display contrast on flat panel displays. The
minimum contrast value and the foreground /
background grayscale adjustment values are
programmed in the 65540 / 545's Extension
Registers. This feature can be disabled if desired.
Introduction / Overview
Revision 1.2 14 65540 / 545