am79c974 Advanced Micro Devices, am79c974 Datasheet - Page 45

• Manufacturer Part Number: am79c974
• Description: Pcnettm-scsi Combination Ethernet And Scsi Controller For Pci Systems
• Manufacturer: Advanced Micro Devices

When SSIZE32 = 1, software data structures are 32 bits
wide. The following diagram illustrates, Figure 18, the
relationship between the Initialization Base Address,
the Initialization Block, the Receive and Transmit
TLEN RES RLEN RES
IADR[31:16]
CSR2
RES
32-Bit Base Address
Initialization Block
Figure 18
Initialization
Pointer to
PADR[31:0]
LADRF[31:0]
LADRF[63:32]
RDRA[31:0]
TDRA[31:0]
Block
.
32-Bit Data Structures: Initialization Block and Descriptor Rings
PADR[47:32]
IADR[15:0]
CSR1
MODE
P R E L I M I N A R Y
Am79C974
Buffers
Buffers
Rcv
Xmt
Descriptor Ring Base Addresses, the Receive and
Transmit Descriptors and the Receive and Transmit
Data Buffers, for the case of SSIZE32 = 1.
1st desc.
start
RMD0
1st desc.
start
TMD0
RX DESCRIPTOR RINGS
RX DESCRIPTOR RINGS
Buffer
Buffer
Data
Data
1
1
RMD1 RMD2 RMD3
N
Rcv Descriptor
TMD1 TMD2 TMD3
Xmt Descriptor
M
Ring
Ring
Buffer
Buffer
N
Data
Data
2
2
M
N
M
2nd desc.
start
2nd desc.
start
RMD0
N
TMD0
M
•
Buffer
Buffer
Data
Data
•
•
M
N
AMD
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18681A-22
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