
IBM3206K0424
IBM Processor for Network Resources
Preliminary
General Purpose DMA (GPDMA)
Page 180 of 676
pnr25.chapt04.01
August 14, 2000
27
Little Endian Mode
When this bit is written to 
’
0
’
, this DMA channel operates in big endian mode. When 
’
1
’
, it 
operates in little endian mode. When in little endian mode, both the source and destina-
tion must be aligned on four-byte boundaries.
26
Reserved
Reserved.
25
Hold Mode
When set, bits 28-29 are redefined to allow the source or destination address to be held 
instead of incremented. Bit 29 becomes the hold destination address and bit 28 becomes 
the hold source address. The address being held must be a register address. When hold-
ing, the maximum length is 240 bytes.
24
Reserved
Reserved.
23
Assume 64
Assume the PCI Interface is 64-bits wide.
22
Assume 32
Assume the PCI Interface is 32-bits wide.
21
Register/Memory 
Destination Address
If this bit is set, the destination address is a register address. If this bit is not set, the des-
tination address is a memory address. If the destination address is a system address, 
this bit should cleared. I/O DMA cycles on the PCI bus are not implemented.
20
System/IBM3206K0424 
Destination Address
If this bit is set, the destination address is a PCI bus address. If this bit is not set, the des-
tination address is internal to the chip.
19
Data/Address Source 
Address
If this bit is set, the Source Address Register contains the source data. If this bit is not 
set, the Source Address Register contains the source address.
18
Reserved
Reserved.
17
Register/Memory 
Source Address
If this bit is set, the source address is a register address. If this bit is not set, the source 
address is a memory address. If the source address is a system address, this bit should 
cleared. I/O DMA cycles on the PCI bus are not implemented.
16
System/IBM3206K0424 
Source Address
If this bit is set, the source address is a PCI bus address. If this bit is not set, the source 
address is internal to the chip.
15-0
Byte Transfer Count
These bits indicate the number of bytes to transfer. A non-zero value in this field starts 
the DMA transfer.
Bit(s)
Function
Description