7220 Datasheet, PDF (109/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

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 00E616 to 00E916) and then by specifying the color register with the CRT display RAM.
There are 3 color outputs: R, G, and B. By a combination of these outputs, it is possible to set 2³ – 1 (no
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
Color register n (CO0 to CO3) (n = 0 to 3) [Addresses 00E616 to 00E916]
B
Name
Functions
After reset R W
0 Nothing is assigned. This bit is a write disable bit.
When this bit is read out, the value is “0.”
0 R—
1 B signal output
selection bit (COn1)
2 G signal output
selection bit (COn2)
0 : No character is output
1 : Character is output
0 : No character is output
1 : Character is output
0 RW
0 RW
3 R signal output
selection bit (COn3)
0 : No character is output
1 : Character is output
0 RW
4 B signal output (background) 0 : No background color is output
0 RW
selection bit (COn4)
1 : Background color is output _{(See note 1)}
5 OUT1 signal output
control bit (COn5)
0 : Character is output
1 : Blank is output
0 RW
(See notes 1, 2)
6 G signal output (background) 0 : No background color is output
selection bit (COn6)
1 : Background color is output
0 RW
7 R signal output (background) 0 : No background color is output
0 RW
selection bit (COn7)
1 : Background color is output _{(See note 2)}
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.
Fig. 2.11.12 Color register n (addresses 00E616 to 00E916)
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7220 Group User’s Manual