7220 datasheet(105/303 Pages) RENESAS

105 / 303 page

2-78

7220 Group User’s Manual

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).

Fig. 2.11.10 Example of display character data storing form

10XX016

+80016

11XX016

+80016

10XXF16

+80016

11XXF16

+80016

10XX016

11XX016

10XXF16

11XXF16

7220 Datasheet(PDF) 105 Page - Renesas Technology Corp