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Bit 5
next OUT instruction loads the data register.
The flip-flop toggles each time an OUT is issued
to the Attribute Controller.
Palette Address Source-When loading the color
palette registers, bit 5 must be cleared to O. To
enable the memory data to access the color
palette, bit 5 must be set to 1.
Palette Register Hex 00 through Hex OF
This is a write-only register. The processor output port is hex
3eo.
Attribute Address Register Format
Bit
7
6
5
4
3
2
1
0
II
I
l.
~ ~
I.
_I _I I_I
~.::
Attribute Address
-
-
Palette Address Source
Not Used
Bit O-Bit 5
Palette-These 6-bit registers allow a dynamic
mapping between the text attribute or graphic
color input value and the display color in the
CRT screen. A logical 1 selects the appropriate
color. A logical 0 de-selects. The color palette
register should be modified only during the
vertical retrace interval to avoid glitches in the
displayed image. Note that some color monitors
do not have an intensity input and only a
maximum of eight colors are be available.
Monitors with four color inputs display sixteen
colors, and monitors with six color inputs display
64 colors.
IBM Enhanced Graphics Adapter 57
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