7220 Datasheet, PDF (105/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

FUNCTIONAL DESCRIPTION
2.11 CRT display function
2.11.3 Memory for display
There are 2 types of display memory: CRT display ROM (addresses 1000016 to 11FFF16) used to store
(masked) character dot data and CRT display RAM (addresses 060016 to 06B716) used to specify the colors
and characters to be displayed. Each type of display memory is described below.
(1) CRT display ROM (addresses 1000016 to 11FFF16)
CRT display ROM stores dot pattern data for characters to be displayed. When actually displaying
characters stored in this ROM, it is necessary to specify them by writing the character code inherent
to each character (code determined based on the addresses in CRT display ROM) into CRT display
RAM.
CRT display ROM has a capacity of 8 K bytes. Since 32 bytes are required for 1 character data, the
ROM can stores up to 256 kinds of characters.
CRT display ROM is broadly divided into 2 areas. The [vertical 16 dots] ! [horizontal (left side) 8
dots] data of display characters are stored in addresses 1000016 to 107FF16 and 1100016 to 117FF16;
the [vertical 16 dots] ! [horizontal (right side) 4 dots] data of display characters are stored in
addresses 1080016 to 10FFF16, 1180016 to 11FFF16 (refer to “Figure 2.11.10”). Note however that the
high-order 4 bits of the data to be written to addresses 1080016 to 10FFF16 and 1180016 to 11FFF16
must be set to “1” (by writing data FX16).
10XX016
or
11XX016
10XXF16
or
11XXF16
b7
b0
00 0 0 0 0 0 0
00 0 0 0 1 00
00 0 0 0 1 00
00001010
00001010
00010001
00 0 1 0 0 01
00 0 1 0 0 01
00100000
00100000
00111111
01000000
01000000
01 0 0 0 0 00
00 0 0 0 0 00
00 0 0 0 0 00
10XX016
+80016
or
11XX016
+80016
10XXF16
+80016
or
11XXF16
+80016
b7
b3
b0
11110000
11110000
11110000
11110000
11110000
1111 00 00
11110000
11110000
11111000
11 11 10 00
11 11 10 00
11110100
11110100
11110100
1111 00 00
11110000
Fig. 2.11.10 Example of display character data storing form
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7220 Group User’s Manual