7220 Datasheet, PDF (112/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

FUNCTIONAL DESCRIPTION
2.11 CRT display function
2.11.6 Character border function
An border of 1 clock (1 dot) equivalent size can be
added to a display character in both horizontal and
vertical directions. The border is output from pin
OUT 1. In this case, set bit 5 of a color register to
“0” (character is output).
Border can be specified each block by the border
selection register (address 00E516). Table 2.11.6
shows the relationship between the set values of
the border selection register and the character border
function. Figure 2.11.16 shows the border selection
register.
Character
data dots
Border dots
Fig. 2.11.15 Border example
Table 2.11.6 Relationship between set value of border selection register and character border function
Border selection register
MDn0
Functions
Example of output
R, G, B output
0
Ordinary
OUT1 output
Border including
R, G, B output
1
character
OUT1 output
Border Selection Register
b7 b6 b5 b4 b3 b2 b1 b0
Border selection register (MD) [Address 00E516]
B
Name
Functions
After reset R W
0 Block 1 OUT1 output
0 : Same output as character output Indeterminate R W
border selection bit (MD10) 1 : Border output
1 Nothing is assigned. This bit is a write disable bits.
When this bit is read out, the value is “0.”
0
R—
2 Block 1 OUT1 output
0 : Same output as character output Indeterminate R W
border selection bit (MD20) 1 : Border output
3
to
7
Nothing is assigned. These bits are write disable bits.
When these bits are read out, the values are “0.”
0
R—
Fig. 2.11.16 Border selection register (address 00E516)
7220 Group User’s Manual
2-85