82596CA Datasheet, PDF (29/76 Pages) Intel Corporation – HIGH-PERFORMANCE 32-BIT LOCAL AREA NETWORK COPROCESSOR

82596CA
Command Word
31
16
ACK
0
CUC
R
RUC
0 0 0 0 SCB a 2
These bits specify the action to be performed as a result of a CA This word is set by the CPU and cleared by
the 82596 Defined bits are
Bit 31 ACK-CX
Acknowledges that the CU completed an Action Command
Bit 30 ACK-FR
Acknowledges that the RU received a frame
Bit 29 ACK-CNA
Acknowledges that the Command Unit became not active
Bit 28 ACK-RNR
Acknowledges that the Receive Unit became not ready
Bits 24–26 CUC
(3 bits) This field contains the command to the Command Unit Valid values are
0
NOP (does not affect current state of the unit)
1
Start execution of the first command on the CBL If a command is executing
complete it before starting the new CBL The beginning of the CBL is in CBL
OFFSET (address)
2
Resume the operation of the Command Unit by executing the next command
This operation assumes that the Command Unit has been previously sus-
pended
3
Suspend execution of commands on CBL after current command is complete
4
Abort current command immediately
5
Loads the Bus Throttle timers so they will be initialized with their new values
after the active timer (T-ON or T-OFF) reaches Terminal Count If no timer is
active new values will be loaded immediately This command is not valid in
82586 mode
6
Loads and immediately restarts the Bus Throttle timers with their new values
This command is not valid in 82586 mode
7
Reserved
Bit 23 RESET
Bits 20–22 RUC
Reset chip (logically the same as hardware RESET)
(3 bits) This field contains the command to the Receive Unit Valid values are
0
NOP (does not alter current state of unit)
1
Start reception of frames The beginning of the RFA is contained in the RFA
OFFSET (address) If a frame is being received complete reception before
starting
2
Resume frame reception (only when in suspended state)
3
Suspend frame reception If a frame is being received complete its reception
before suspending
4
Abort receiver operation immediately
5–7 Reserved
29