Intel 82558 Manuale Utente

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The CBL consists of a linked list of individual action commands in structures called Command 

Blocks (CBs). The CBs contain command parameters and status of the action commands. Action 
commands are categorized as follows:

•

Non-transmit (non-Tx) commands: This category includes commands such as no operation 

(NOP), Configure, IA Setup, Multicast Setup, Dump and Diagnose.

•

Transmit (Tx) command: This includes Transmit Command Blocks (TxCB).

The Receive Frame Area (RFA) consists of a list of Receive Frame Descriptors (RFDs) and a list of 

user-prepared or NOS provided buffers. The receive architecture supports the simplified memory 

model similar to the way it is supported by the transmit command. In the simplified memory 
model, the data buffer immediately follows the RFD. The receive structures format and receive 

code flow is described in 

 and 

.

The LAN controller also provides read and write access to an external EEPROM and the 
Management Data Interface (MDI) registers. This is achieved through the EEPROM Control 

Register and the MDI Control Register, respectively. These registers occupy offsets 0Ch through 
14h of the CSR.

10/100 Mbps Device (8255x) Registers

System Control

Block (SCB)

Buffer Descriptor

Buffer Descriptor

Frame Descriptor

Frame Descriptor

Frame Descriptor

Control Block

Control Block

Control Block

Buffer Descriptor

Receive Data

Buffer

Receive Data

Buffer

Receive Data

Buffer

Command Block List (System Memory)

Receive Frame Area (System Memory)