IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

Modes of Operation
The IBM Monochrome Display and Printer Adapter supports 256
character codes. In the character set are alphanumerics and block
graphics. Each character in the display buffer has a corresponding
character attribute. The character code must be an even address and the
attribute code must be an odd address in the display buffer. ,.............,
7 6 5 4 3 2 o
7 6 5 4 3 2 0
BL R I R B
CHARACTER CODE
EVEN ADDRESS (M)
ATTRIBUTE CODE
I G I B I I G ODD ADDRESS (M+l)
I
I ..
FOREGROUND
~
: INTENSITY
BACKGROUND
~
... BLINK
The adapter decodes the character attribute byte as defined above. The ,.............,
BLINK and INTENSITY bits may be combined with the FORE­
GROUND and BACKGROUND bits to further enhance the character
attribute functions listed below.
BACKGROUND FOREGROUND FUNCTION
R G B
R G B
0 0 0 0 0 0 NON DISPLAY
0 0 0 0 0 1 UNDERLINE
0 0 0 1 1 1 WHITE CHARACTER/
BLACK BACKGROUND
1 1 1 000 REVERSE VIDEO
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