
168
Registers
Chapter 4
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
Note that not all bits in the command and mode registers of legacy DMA controllers are used in the
IC’s DMA controller. The bit usage for these registers are as follows.
Note:
DMA channel 4 is hardwired into cascade mode; however is obsolete for all other channels.
For debug purposes writes to the DMA page registers at 0x80 to 0x87 show up on PCI and LPC. It is
expected that no external device claims these cycles nor responds to these cycles.
Table 50.
DMA Controller Register Summary
Name
Base Address Registers
Base Word Count Registers
Current Address Registers
Current Word Count Registers
Status Registers
Command Registers
Mode Registers
Mask Registers
Note:
Although channel 4 base and current registers exist for compatibility, they are not used.
Size
16 bits
16 bits
16 bits
16 bits
8 bits
1 bit
5 bits
4 bits
Number Comments
8
1 for each channel (0-7) (see note)
8
1 for each channel (0-7) (see note)
8
1 for each channel (0-7) (see note)
8
1 for each channel (0-7) (see note)
2
1 for Master and 1 for Slave DMAC
2
1 for Master and 1 for Slave DMAC
8
1 for each channel (0-7) (see note)
2
1 for Master and 1 for Slave DMAC
Table 51.
DMA Command Register Bits (Master and Slave DMAC)
Bit
7
6
5
4
3
2
1
0
8237 Function
DACK sense
DREQ sense
Late/Extended write
Fixed/Rotating priority
Normal/Compressed timing
Controller enable/disable
Ch0 address hold enable/disable
Memory-to-memory enable/disable
DMAC Function of the IC
Obsolete
Obsolete
Obsolete
Obsolete (always
fi
xed priority)
Obsolete
Controller enable/disable
Obsolete
Obsolete
Table 52.
DMA Mode Register Bits (Master and Slave DMAC)
Bit
7:6
8237 Function
00b Demand mode select
01b Single mode select
10b Block mode select
11b Cascade mode select
Address increment/decrement select
Auto initialization enable/disable
00b Verify transfer
01b Write transfer
10b Read transfer
11b Illegal
Channel select
DMAC Function of the IC
00b Demand mode select
01b Single mode select
10b Obsolete
11b Obsolete
Obsolete (always increment)
Auto initialization enable/disable
00b Verify transfer
01b Write transfer
10b Read transfer
11b Illegal
Channel select
5
4
3:2
1:0