Display Controller ICThe CSC (color support chip) IC provides the data and control interface to the LCD
panel. The CSC IC is also used in the Macintosh PowerBook 500 and 280 series
computers. The CSC IC contains a 256-entry CLUT, RAMDAC, display buffer controller,
and flat panel control circuitry. For more information, see “Displays” on page 14.
___________________________________________________________________________
The color display can operate in either of two modes. In 8-bit mode the display has a
640-by-480-pixel area and can display up to 256 different colors at a time. In 16-bit mode
the display has a 640-by-400-pixel area and can display thousands of colors.
The user can select either color display mode by using the Monitors control panel.
Because the VRAM is a fixed size, 256K by 16 bits, it can handle only a certain amount of
data. When the user selects 16-bit mode, the system software resizes the display area
down to 400 lines instead of 480 and centers the display area on the screen, leaving black
bands of 40 lines each at the top and bottom of the screen.
Note
The number of colors available in 16-bit mode is less than the theoretical
maximum due to the limitations in the color LCD technology. Many
color values exhibit noticeable flicker. The computer’s CLUT omits the
unsatisfactory colors, making about 4000 available. See the appendix,
“Color Lookup Table,” for more information.
