82091AA datasheet(34/204 Pages) INTEL

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82091AA

Bit

Description

NOT USED

Always write to 0

VOLTAGE SELECT (VSEL)

This bit indicates whether 33V or 5V has been selected for the

operating power supply voltage during hardware configuration A 1 indicates that 33V is selected

and a 0 indicates that 5V is selected This bit is read only and writes have no effect

NOTE

33V operation is available only in the 82091AA

CONFIGURATION MODE SELECT (CFGMOD)

These bits indicate the configuration mode for the

82091AA After a hard reset these bits reflect the mode selected by hardware configuration If

configuration register access is not locked out during hardware configuration software can change

the configuration mode by writing to this field For configuration mode details (see Section 42

Hardware Configuration)

Bits 54

Configuration Mode

0 0

Software Motherboard (SWMB)

0 1

Software Add-in (SWAI)

1 0

Extended Hardware (HWE)

1 1

Basic Hardware (HWB)

CONFIGURATION ADDRESS SELECT (CFGADS)

This read only bit indicates the address

assignment for the 82091AA configuration registers as selected by hardware configuration

Hardware configuration selects between primary addresses (22h23h and 26Eh26Fh) and

secondary addresses (24h25h and 398h399h) for accessing the 82091AA configuration registers

When CFGADSe0 the primary addresses are selected and when CFGADSe1 the secondary

addresses are selected

RESERVED

CLOCK OFF (CLKOFF)

The CLKOFF bit is used to implement clock circuitry power management

When CLKOFFe0 the main clock circuitry is powered on When CLKOFFe1 the main clock

circuitry is powered off This capability is independent of the 82091AA’s powerdown state Note that

auto powerdown mode and powerdown have no effect over the power state of the clock circuitry

415 AIPCFG2AIP CONFIGURATION 2 REGISTER

Index Address

03h

Default Value

0000 0RRR

Attribute

ReadWrite

Size

8 bits

This register selects the active signal level for IRQ 73

The interrupt signals can be individually programmed

for either active high or active low drive characteristics The active high mode is ISA (non-share) compatible

and has tri-state drive characteristic The active low mode is EISA (sharable) compatible and has an open

collector drive characteristic

82091AA Datasheet(PDF) 34 Page - Intel Corporation

82091AA Datasheet(HTML) 34 Page - Intel Corporation

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