Modes
of
Operation
There are two basic modes
of
operation, 'Alphanumeric' and
'Graphics'.
Each
of
these modes provide further options in both color
and black-and-white. The following text describes each mode
of
operation.
~
Alphanumeric Mode
Alphanumeric Display Architecture
Every display character position is defined by two bytes in the regen
buffer (part
of
display adapter, not system memory). Both the color and
the black and white display adapter use this 2 byte character/attribute
format.
DISPLAY
CHAR
CODE
BYTE
ATTRIBUTE
BYTE
6 5 4 3 6 4
Attribute Byte Definition
ATTRIBUTE
BYTE
765
4
3 2
o
B R G B I R
G B
ATTRIBUTE
FUNCTION
FG
BACKGROUND
FOREGROUND
NORMAL
B
0
0 0 I 1 1
1
REVERSE
VIDEO
B
1 1 1
I
0 0
0
NON
DISPLAY
(BLK)
B
0 0 0 I
0 0
0
NON
DISPLAY
(WHITE)
B
1 1 1 I 1
1 1
I =
HIGH
LIGHT
FOREGROUND
(CHAR)
B=
BLINK
FOREGROUND
(CHAR)
Color
TV
• Display up to
25
rows
of
40
characters each
• Maximum
of
256 characters
• Requires 2000 bytes
of
Read/Write Memory (on the adapter)
• 8x8 character box
• 7x7 double dotted characters (one descender)
• Character attributes (one for each character)
2-49
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