AGB Programming Manual
DMA Transfer
©1999 - 2001 Nintendo of America Inc.
113
D.C.N. AGB-06-0001-002B4
12.2 DMA 1 and 2
DMA channels 1 and 2 provide access between the Game Pak bus/internal memory of
the main unit and internal memory of the main unit, or between the Game Pak
bus/internal memory of the main unit and the direct sound FIFO. Transfers to direct-
sound FIFO can be accomplished only by using DMA 1 and 2.
1) Source Address
Specifies the source address using 28 bits.
The area 00000000h-0FFFFFFFh can be specified.
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
DMA1SAD_L
DMA2SAD_L
0BCh
0C8h
0000h
W
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
DMA1SAD_H
DMA2SAD_H
0BEh
0CAh
0000h
W
Address
Register
Attributes
Initial
Value
Address
Register
Attributes
Initial
Value
2) Destination Address
Specifies the destination address using 27 bits.
The area 00000000h-07FFFFFFh (internal memory area of main unit) can
be specified.
15
14 13
12
11 10
09
08 07
06
05 04
03
02 01
00
DMA1DAD_L
DMA2DAD_L
0C0h
0CCh
0000h
W
15
14 13
12
11 10
09
08 07
06
05 04
03
02 01
00
0C2h
0CEh
0000h
W
DMA1DAD_H
DMA2DAD_H
Address
Register
Attributes
Initial
Value
Address
Register
Attributes
Initial
Value
3) Word Count
Specifies the number of bytes transferred by DMA 1 and DMA 2, using 14
bits. The number can be specified in the range 0001h~3FFFh~0000h
(when 0000h is set, 4000h bytes are transferred).
Thus, in 16-bit data transfer mode, up to 4000h x 2=8000h bytes can be
transferred, and in 32-bit data transfer mode, up to 4000h x 4=10000h
bytes can be transferred.
15
14
13 12
11
10 09
08
07 06
05
04 03
02 01
00
0C4h
0D0h
0000h
W
DMA1CNT_L
DMA2CNT_L
Address
Register
Attributes
Initial
Value
The word-count register setting is disabled in direct-sound FIFO transfer
mode. With each request received from sound FIFO, 32 bits x 4 words of
sound data are transferred.