Nintendo GAME BOY ADVANCE Programming Manual page 42

20
DISPCNT [d07] Forced Blank
Setting this bit causes the CPU to forcibly halt operation of the image processing circuit, allowing
access to VRAM, color palette RAM, OAM, and the internal registers. The LCD screen displays white
during a forced blank. However, the internal HV synchronous counter continues to operate even during
a forced blank. When the internal HV synchronous counter modifies the forced blank setting during a
display period, the forced blank occurs immediately when switching from ON to OFF, but the forced
blank only occurs after displaying three vertical lines when switching from OFF to ON.
DISPCNT [d06] OBJ Character VRAM Mapping Format
Specifies the VRAM mapping format for an OBJ character.
A setting of 0 causes the OBJ character to be handled in memory mapped 2-dimensional. A se tting of
1 causes the OBJ character to be handled in memory mapped 1-dimensional.
For information on OBJ character VRAM mapping formats, see
page 48.
DISPCNT [d05] H-Blank Interval OBJ Processing Flag
A setting of 0 executes OBJ Render Processing with all H- Line intervals (including H-Blank intervals).
A setting of 1 executes OBJ Render Processing with the display intervals only and not for H-Blank
intervals. Thus, when the user accesses OAM or OBJ VRAM during an H-Blank interval, this bit needs
to be set. However, also in this situation, maximum OBJ display performance cannot be obtained.
DISPCNT [d04] Display Frame Selection
When rendering in bitmap format in a mode in which there are 2 frame buffers (BG modes 4 and 5),
this bit allows selection of one of the frame buffers for rendering. A setting of 0 selects the contents of
frame buffer 0 for rendering; a setting of 1 selects the contents of frame buffer 1 for rendering.
DISPCNT [d03] (CGB Mode)
Game Boy Advance is equipped with two CPUs. In Game Boy Advance mode, a 32-bit RISC CPU
starts, and in CGB mode, an 8-bit CISC CPU starts.
Because this bit is controlled by the system, it cannot be accessed by the user.
Note:
DISPCNT [d02-00] BG Mode
Selects the BG mode from a range of 0-5.
For more information on BG modes, see
AGB-06-0001-002-B13
Released: May 27, 2005
Game Boy Advance Programming Manual
"5.1 BG Modes" on page 21.
"6.3.2 Character Data Mapping" on
© 1999-2005 NINTENDO
May 25, 2005