ELSA Synergy 2000, Руководство пользователя

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Graphics know-how
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| ELSA Synergy 2000 |
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EN
4.2.6 DirectColor
The situation is different in the case of DirectColor (TrueColor and HighColor).
In this case, the value stored in the video memory is not translated but is
passed directly to the D/A converter. This means that the full color informa-
tion must be saved for each pixel. The meanings of the terms TrueColor and
HighColor can be confused, as they are not always used unambiguously.
HighColor
HighColor usually describes a 16-bit wide graphics mode, while TrueColor
should only be used for the more professional 24-bit mode (or 32-bit) mode.
Most common are (R-G-B) 5-6-5 (e.g. XGA) and 6-6-4 (e.g. i860). 5-6-5 means
that 5 bits are used for each of red and blue and 6 bits are used for green. In
the case of 6-6-4, 6 bits are used for red and green and 4 bits for blue. Both
ways of assigning the bits correspond to the color sensitivity of the human
eye: this is highest for green and lowest for blue. 65,536 different colors can
be displayed.
TrueColor
The TrueColor mode is more complex, using 24 bits per pixel. Here, 8 bits are
available for each color component (256 levels), resulting in 16.7 million dif-
ferent color hues. There are more colors available than pixels on the screen
(1.3 million pixels at a resolution of 1280 x 1024).
4.2.7 VESA DDC (Display Data Channel)
The Display Data Channel provides a serial data channel between the moni-
tor and the graphics board, as long as both support DDC and the monitor
cable includes the additional DDC wire. An extended monitor cable is used.
This feature allows the monitor data to be sent automatically to the graphics
board (e.g. name, type, max. horizontal frequency, timing definitions etc.) or
even for the graphics board to send instructions to the monitor.
There are various standards; DDC2B and DDC2AB.
4.2.8 DDC2B
A bi-directional data channel based on the I
2
C access-bus protocol is used for
the communication between monitor and graphics board. In the case of a
standard IBM VGA compatible 15-pin monitor connector, pin 12 (formerly
used as monitor ID bit 1) is used for data transmission (SDA), and the pin 15