AMD-761 datasheet(74/264 Pages) AMD

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AMD-761™ System Controller Programmer’s Interface

Chapter 2

AMD-761™ System Controller Software/BIOS Design Guide

24081D—February 2002

Preliminary Information

Bit Definitions

BIU0 Status/Control (Dev0:F0:0x60)

Bit

Name

Function

Prb_En

Probe Enable

0 = Probes are not sent to this processor.

1 = Probes are sent to this processor.

Reserved

This bit must be programmed to zero for normal operation.

Reserved

This bit must be programmed to zero for normal operation.

Reserved

This bit must be programmed to zero for normal operation.

27–25

Xca_Prb_Cnt

Xca Probe Count

This bit field represents the maximum number of consecutive AMD Athlon™ processor

system bus grants for probe data movement types that are allowed before letting another

type have the bus.BIOS must program this field to a non-zero value for proper operation.

The recommended value to be loaded in this field by BIOS software is 0x2.

24–22

Xca_RD_Cnt

Xca Read Count

This bit field represents the maximum number of consecutive AMD Athlon processor

system bus grants for read data movement types that are allowed before letting another

type have the bus.BIOS must program this field to a non-zero value for proper operation.

The recommended value to be loaded in this field by BIOS software is 0x6.

21–19

Xca_WR_Cnt

Xca Write Count

This bit field represents the maximum number of consecutive AMD Athlon processor

system bus grants for write data movement types that are allowed before letting another

type have the bus.BIOS must program this field to a non-zero value for proper operation.

The recommended value to be loaded in this field by BIOS software is 0x6.

Halt_Discon_En

Halt Disconnect Enable

0 = No AMD Athlon system bus disconnect is performed following HALT.

1 = AMD Athlon system bus disconnects after receiving a HALT special cycle.

Stp_Grant_

Discon_En

Stop Grant Disconnect Enable

0 = No AMD Athlon processor system bus disconnect is performed following STOP/GRANT.

1 = AMD Athlon processor system bus disconnects after receiving a STOP/GRANT special cycle.

16–14

Prb_Limit

Probe Limit

BIOS software initializes this field with the maximum number of outstanding probes that

the given CPU can handle. The default is a single probe. Encoding is as follows:

0b000 = 1 probe

0b001 = 2 probes

................................

0b111 = 8 probes

13–10

Ack_Limit

Ack Limit

BIOS software reads this field to determine how many outstanding unacknowledged

AMD Athlon processor system bus commands can be sent to the AMD-761™ system

controller. The AMD-761 system controller allows a maximum of four unacknowledged

commands. Encoding is as follows:

0b0000 = 1 unacknowledged command

0b0001 = 2 unacknowledged commands

..........................................................

0b1111 = 16 unacknowledged commands

AMD-761 Datasheet(PDF) 74 Page - Advanced Micro Devices

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