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7220 Group User’s Manual

2.11 CRT display function

2.11.8 Raster coloring function

R, G, B, and OUT1 output can be switched to MUTE output. MUTE output can color all displaying area

(raster) of screen.

For example, the case that pin B is specified for MUTE signal output is shown in Figure 2.11.18.

When the MUTE signal is output from pin B, the background of the entire screen is colored “BLUE.” Then,

a character data is output from pin R, for example. When B and R signal outputs are set to “character is

output” by the color register at the character “I” output, the output character is colored “YELLOW” (“RED”

mixed “BLUE”) regardless of the OUT1 signal output.

When outputting the character “O,” the output character is colored only “RED” that is not mixed “BLUE”

by setting only R signal output to “character is output.” However, in this case, set pin OUT1 to “blank is

output.”

The TV image can be also erase by setting the all R, G, and B pins to MUTE output. The MUTE signal

is output from pin OUT1 output, regardless of setting CRT display RAM for pin OUT1.

Whether ordinary video signal outputs or MUTE signal outputs from pins R, G, and B is controlled by bits

5 to 7 of the CRT port control register (refer to “Figure 2.11.17”).

Fig. 2.11.18 MUTE signal output example

“RED”

“BLUE”

HSYNC

OUT 1

Signals across

A-A'

FUNCTIONAL DESCRIPTION

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