Nintendo 1504166 - Game Boy Advance SP Edition Console Programming Manual page 44

AGB Programming Manual
[d09-00] Character Name
Specify the number of the character that has character base block starting
address specified in the BG control register as its starting point.
2) Rotation/Scaling BG Screen
The rotation/scaling BG screen consists of 1 byte of screen data per basic
character; 256 character types can be specified.
The character data must be classified as 256 colors x 1 palette.
The color mode specification in the BG control register is disabled for a
rotation/scaling screen.
[Cautions for VRAM]
AGB provides a high degree of freedom in using the BG area of VRAM.
Consequently, in managing VRAM, the following points deserve particular
attention.
1. There are 2 formats for BG character data (defined by 16 and 256
colors), and these can be used together.
2. The BG character data base block can be selected from among 4
blocks (BG control register).
3. The BG screen data base block can be selected from among 32
blocks (BG control register).
4. The screen size (amount of VRAM used) can be set for each BG (BG
control register).
5. Text and rotation/scaling BGs can be present and used together in a
BG screen.
In managing VRAM, particular care is required in BG mode 1, because text
BG screens (which can handle BG character data in both 256 colors x 1
palette and 16 colors x 16 palettes) and rotation/scaling BG screens
(which can handle only 256 colors x 1 palette) may be used together.
Therefore, the VRAM mapping status should be sufficiently understood
when programming.
©1999 - 2001 Nintendo of America Inc.
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Character Name
44
Rendering Functions
D.C.N. AGB-06-0001-002B4