82596DX Datasheet, PDF (35/77 Pages) Intel Corporation – HIGH-PERFORMANCE 32-BIT LOCAL AREA NETWORK COPROCESSOR

82596DX SX
ACTION COMMANDS AND OPERATING MODES
This section lists all the Action Commands of the Command Unit Command Block List (CBL) Each command
contains the Command field the Status and Control fields the link to the next Action Command and any
command-specific parameters There are three basic types of action commands 82596 Configuration and
Setup Transmission and Diagnostics The following is a list of the actual commands
 NOP
 Transmit
 Individual Address Setup
 TDR
 Configure
 Dump
 MC Setup
 Diagnose
The 82596 has three addressing modes In the 82586 mode all the Action Commands look exactly like those
of the 82586
 82586 Mode The 82596 software and memory structure is compatible with the 82586
 32-Bit Segmented Mode The 82596 can access the entire system memory and use the two new memory
structures Simplified and Flexible while still using the segmented approach This does not require any
significant changes to existing software
 Linear Mode The 82596 operates in a flat linear 4 gigabyte memory space without segmentation It can
also use the two new memory structures
In the 32-bit Segmented mode there are some differences between the 82596 and 82586 action commands
mainly in programming and activating new 82596 features Those bits marked ‘‘don’t care’’ in the compatible
mode are not checked however we strongly recommend that those bits all be zeroes this will allow future
enchancements and extensions
In the Linear mode all of the address offsets become 32-bit address pointers All new 82596 features are
accessible in this mode and all bits previously marked ‘‘don’t care’’ must be zeroes
The Action Commands and all other 82596 memory structures must begin on even byte boundaries i e they
must be word aligned
NOP
This command results in no action by the 82596 except for those performed in the normal command process-
ing It is used to manipulate the CBL manipulation The format of the NOP command is shown in Figure 21
NOP 82586 and 32-Bit Segmented Modes
31
ODD WORD
16 15
EVEN WORD
0
EL S I X X X X X X X X X X 0 0 0 C B OK 0 0 0 0 0 0 0 0 0 0 0 0 0 0
X X X X X X X X X X X X X X X X A15
LINK OFFSET
A0 4
NOP Linear Mode
31
ODD WORD
16 15
EVEN WORD
0
EL S I 0 0 0 0 0 0 0 0 0 0 0 0 0 C B OK 0 0 0 0 0 0 0 0 0 0 0 0 0 0
A31
LINK ADDRESS
A0 4
Figure 21
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