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FUNCTIONAL DESCRIPTION
2.11 CRT display function
2.11.4 Color registers
A display character color can be specified by setting a color to one of 4 color registers (CO0 to CO3:
addresses 00E6
to 00E9
16
There are 3 color outputs: R, G, and B. By a combination of these outputs, it is possible to set 2
output) = 7 colors. However, since color registers are only 4, up to 4 colors can be displayed at one time.
R, G, and B outputs are set by bits 1 to 3 of the color register. Bit 5 is used to specify either a character
output or blank output. Figure 2.11.12 shows the color register.
Either character output or blank output is selected as the OUT1 pin output. Whether blank output or not
is selected as the OUT2 pin output.
Color Register n
b7 b6 b5 b4 b3 b2 b1 b0
Fig. 2.11.12 Color register n (addresses 00E6
2-82
) and then by specifying the color register with the CRT display RAM.
16
Color register n (CO0 to CO3) (n = 0 to 3) [Addresses 00E6
B
Name
0
Nothing is assigned. This bit is a write disable bit.
When this bit is read out, the value is "0."
1
B signal output
selection bit (COn1)
G signal output
2
selection bit (COn2)
3
R signal output
selection bit (COn3)
4
B signal output (background)
selection bit (COn4)
5
OUT1 signal output
control bit (COn5)
6
G signal output (background)
selection bit (COn6)
7
R signal output (background)
selection bit (COn7)
Notes 1: When bit 5 = "0" and bit 4 = "1," there is output same as a character or border output
from the OUT1 pin.
Do not set bit 5 = "0" and bit 4 = "0."
2: When only bit 7 = "1" and bit 5 = "0," there is output from the OUT2 pin.
7220 Group User's Manual
Functions
0 : No character is output
1 : Character is output
0 : No character is output
1 : Character is output
0 : No character is output
1 : Character is output
0 : No background color is output
1 : Background color is output
0 : Character is output
1 : Blank is output
0 : No background color is output
1 : Background color is output
0 : No background color is output
1 : Background color is output
to 00E9
)
16
16
to 00E9
]
16
16
After reset R W
0
R —
0
R W
0
R W
0
R W
0
R W
(See note 1)
0
R W
(See notes 1, 2)
0
R W
0
R W
(See note 2)
3
– 1 (no
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