Introduction to PCI System Architecture. Contents: Introduction to PCI System PCI Bus Arbitration...

Introduction to PCI System Architecture

Introduction to PCI System

Direct-Connect Approach(VESA)

CPU Cache

Main memory

Local Bus Memory Bus

Expansion Bridge

ExpansionConnectors

X-Bus Buffer

I/O Device I/O Device I/O Device

Local Bus Design Constraint:

1. Redesign is necessary for next generation processor.

2. Only one local device is permitted.

3. Design of local bus inter -face is difficult.

4. Transfer with one device is not permitted while the local bus is involved in a transfer with another device.

Expansion Bus

X-Bus

Local Bus Device

CPU CacheLocal Bus Memory Bus

Expansion Bridge

X-Bus Buffer

I/O Device I/O Device

Expansion Bus

X-Bus

Bus Buffer

I/O Device

I/ODevice

I/ODevice

I/ODevice

Buffered Approach(VESA)

Buffered Local Bus

A maximum of three local bus devices can be placed on the buffered local bus.

CPUHost/PCICache/Bridge

Workstation Approach(PCI)

Memory BusCPU Local Bus

Main Memory

Video Memory

Audio PeripheralMotion VideoPeripheral

SCSI Host Bus Adapter

SC

SI B

US

Disk

TapeCD ROM

Expansion Bus

Video Frame Buffer

Graphics Adapter

Expansion BusBridge

LANAdapter

PCI Bus

BusMaster

I/OSlave

MemorySlave

LAN

Transfer Rate Comparison:

Bus Bus Frequency Transfer Transfer Rate

ISA 8.33 MHz 2 byte / 2 clock 8.33 MB/s

EISA 8.33 MHz 4 byte / 1 clock 33 MB/s

( Burst Mode)

VESA 33 MHz 4 byte / 1 clock 132 MB/s

( Read, Burst )

4 byte / 2 clock 66 MB/s

( Write, Burst )

PCI 33 MHz 4 byte / 1 clock 132 MB/s


66 MHz 4 byte / 1 clock 264 MB/s


( Burst Mode )

• PCI: Peripheral Component Interconnect

• Major PCI Revision 2.1 Features

Processor Independence

Support for up to 256 PCI functions per PCI bus

Low power consumption ( Draw as little current as possible )

Burst used for all read and write transfers

Supports 66 MHz operation, 64bit bus width

Fast access ( 60ns at bus speed 33 MHz )

Concurrent bus operation

Bus master support

Hidden bus arbitration

Low pin count ( Initiator:49pins, Target:47 pins )

Transaction integrity check( Parity check)

Three address spaces ( Memory, I/O, Configuration )

Auto configuration( Configuration register )

Software Transparency

AD[31:00] AD[63:32]

C/BE[3:0]# C/BE[7:4]#

PAR

FRAM#

TRDY#IRDY#STOP#DEVSEL#IDSEL

SERR#

REQ#GNT#

CLKRST#

PAR64REQ64#ACK64#

LOCK#

INTA#INTB#INTC#INTD#

TDI

PCICOMPLIANT DEVICE

PERR#

PCI-Compliant Device Signals

TDOTCKTMSTRST#

CLKRUN#

Address/Dataand Command

Interface Control

Error Reporting

Arbitration

System

Required Signals Optional Signals

64-bit Extension

Atomic Access

Interrupt Request

Clock Control

SDONSnoop Result

JTAG

For Slave only

For Master only

SBO#

PCI Bus Arbitration

Initiator/ Target

Initiator ( Master ): The device that initiates a transfer

Target ( Slave ): The device that currently addressed by the initiator for

the purpose of performing a data transfer

PCI Device

PCI Device

PCI Device

PCI Device

PCI Arbiter

REQ0# REQ1# REQ2# REQ3#

GNT0#GNT1# GNT2# GNT3#

PCI Device

MASTER

SLAVE

Address, Command/

Data, Byte Enables/

Parity

DRAM

SLAVE

Bridge

SLAVE

PCI Bus Arbitration Algorithm

First Group

Second Group

Master A

Master B

Master X

Master Y Master Z

A B X A B Y A B Z A B X

• Fairness ( fixed, rotational )

• Bus Parking( on specified master, on last master that acquired the bus )

• Hidden Bus Arbitration( REQ#, GNT#)

• LT ( Latency Timer ): The minimum amount of time that the bus master is

permitted to retain ownership of the bus

AD

REQA#

REQB#

GNTA#

GNTB#

FRAME#

( Master B has higher priority than Master A)

IRDY#

TRDY#

Example of PCI Bus Arbitration Between Two Masters

1 2 3 4 5 6 8

ADDRESS DATA

9 10 11 127

DATA DATA DATAADDRESS DATAADDRESS

A B A

( Master A -> Arbiter )

( Master B -> Arbiter )

( Arbiter -> Master A )

( Arbiter -> Master B )

( Master -> Target )

( Target -> Master )


( Master <-> Target )

CLK

LT not expired

REQ#-

GNT#

DEVSEL#

FRAME#

1 2 3 4 5 6 87CLK

IRDY#

TRDY#

AD ADDRESS DATA ADDRESS DATA

Arbitration for Fast Back-To-Back Accesses

Delayed Transaction

Delayed Transaction

Request Phase:

Completion Phase:

Target latches the request and issues retry

Transaction completes on the target bus

Master

PIIX4

ISA Device

1. Address, Command, Byte Enables latched by PIIX4

2. Retry issued to MTXC

( Request Phase )

3. Requested data fetched in buffer ( Completion Phase )

Target

MTXC

4. Master Retries the transaction with the

same address, command, data

OR no Retry within 215 clocks Discard the data

Target cannot respond within 16 clocks:

Commands That can Use Delayed Transactions

Interrupt Acknowledge I/O Read I/O Write

Memory Read

Memory Read Line

Memory Read Multiple

Configuration Read

Configuration Write

The PCI Commands

C/BE[3::0]# Command Type

0000 Interrupt Acknowledge0001 Special Cycle0010 I/O Read0011 I/O Write0100 Reserved0101 Reserved0110 Memory Read0111 Memory Write1000 Reserved1001 Reserved1010 Configuration Read1011 Configuration Write1100 Memory Read Multiple1101 Dual Address Cycle 1110 Memory Read Line1111 Memory Write and Invalidate

PCI Command Types

C/BE#[3:0] is used to indicate the command or transaction type during the address phase

VECTOR

INT ACK CMD Byte Enables

CLK

FRAME #

AD

C/BE #

IRDY #

TRDY #

1 2 3 4 5

DEVSEL #

GNT #

PCI Interrupt Acknowledge Transaction

Stable Pattern

( Host Bridge -> INT Controller )

( Host Bridge < -> INT Controller )

( Host Bridge -> INT Controller )

( INT Controller-> Host Bridge )

GNT#

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

AD[31:0]

1 2 3 4 5 6 87

Stable Pattern

Message

C/BE#[3:0] Special Cmd

Byte Enables

The Special Cycle Transaction( Halt / Shut Down)

Terminated with Master Abort

• For an initiator to

broad- cast a message

to one or more targets.

• Message type on AD[15:0] • Message-dependent data field on AD[31:16]

• Byte Enable on C/BE#[3:0] 7 clocks

Message Code Message Type

( on AD[15:0]

0000h Shut Down

0001h Halt

0002h x86-specific

message

0003h-ffffh Reserved

The Read and Write Transfers

Read Transaction( 33.33 Mb/s )

CLK1 2 3 4 5 6 7 8 9

FRAME#

AD

C/BE#

IRDY#

TRDY#

DEVSEL#

ADDRESS DATA-1 DATA-2 DATA-3

BUS CMD

ADDRESS PHASE

DATA PHASE

DATA PHASE

DATA PHASE

BYTE ENABLES BYTE ENABLES BYTE ENABLES

Wait state for bus ownership

One more clock before initiator ready to receive data

Some time is needed for fetching data

Avoid bus contention

GNT#

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

AD

1 2 3 4 5 6 87

Address Data1

C/BE# BUSCMD

Byte Enables

Data2 Data3

ByteEnables

ByteEnables

Optimized Read Transaction

( 132 Mb/s)

Burst Transfer:

1. If target memory is

cacheable.

2. If target memory is

prefetchable

CLK1 2 3 4 5 6 7 8 9

FRAME#

AD

C/BE#

IRDY#

TRDY#

DEVSEL#

ADDRESS DATA-1 DATA-2 DATA-3

BUS CMD BYTE ENABLESByte EN Byte EN

Write Transaction

( 44.44 Mb/s )

GNT#

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

AD

1 2 3 4 5 6 87

Address Data1

C/BE# BUSCMD

Data2 Data3

ByteEnables

ByteEnables

Optimized Write Transaction

( 132 Mb/s)

ByteEnables

Addressing

• Addressing Sequence During Memory Burst Linear ( or Sequential ) address mode

Cache Line wrap mode

AD1 AD0 Addressing Sequence

0 0 Linear

0 1 Reserved

1 0 Cacheline wrap

1 1 Reserved

• PCI I/O Addressing AD[31:2] : Target DW of I/O space

AD[1:0] : The Least-significant byte within the DW that the

initiator wishes to transfer with ( 00 = byte 0, 01 = byte 1 )

64 bit PCI Extension

REQ64#, ACK64#, PAR64, AD[64::32], C/BE[7::4]

1 2 3 4 5 6 7 8 9

ADDRESS

DATA-1 DATA-3 DATA-5

DATA-2 DATA-4 DATA-6

BUS CMD BE# ‘s

BE# ‘s

CLK

FRAME#

REQ64#

AD[31::00]

AD[63::32]

C/BE[3::0]#

C/BE[7::4]#

IRDY#

TRDY#

DEVSEL#

ACK64#

64-bit Read Request with 64-bit Transfer

64-bit Write Request with 32-bit Transfer

1 2 3 4 5 6 7 8 9

ADDRESS

DATA-1 DATA-3

DATA-2

BUS CMD BE# ‘s-1

CLK

FRAME#

REQ64#

AD[31::00]

AD[63::32]

C/BE[3::0]#

C/BE[7::4]#

IRDY#TRDY#

DEVSEL#

ACK64#

DATA-2

BE# ‘s-2 BE# ‘s-3

BE# ‘s-2

64-bit Dual Address Read Cycle

1 2 3 4 5 6 7 8

DUAL AD BE# [3::0]

CLK

FRAME#

IRDY#

TRDY#

LO-ADDR HI-ADDR DATA-1 DATA-3AD[31::00]

C/BE[3::0]# BUS CMD

AD[63::32]

C/BE[7::4]#

HI-ADDR DATA-2 DATA-4

BE# [7::4] BUS CMD

DEVSEL#

REQ64#

ACK64#

Premature Transaction Termination

Master Initiated TerminationMaster Initiated Termination

Reasons

Transaction completed normally ( Not premature transaction termination )

Initiator been preempted ( GNT# removed )

Preemption during timeslice by another bus master

Timeslice expiration followed by preemption

Master abort

No target respond to the address ( DEVSEL# not asserted)

No device resides at the address

Special cycle

Configuration accessing a non-existent target

GNT#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4 5 6 7

GNT#

FRAME#

CLK

IRDY#

TRDY#

Preempted

Internal LT time out sensed

Preempted

Time out sensed

Preemption

Example

Timer Expiration Example

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4 5 6 87

Example of Master-abort on Single-Data Phase Transaction

Fast Medium Slow Bridge

Master Abort : Target doesn’t claim transaction

Target Initiated Termination( STOP# )

Disconnect

Target Initiated Termination( STOP# )

Disconnect

Target very slow to complete first data phase ( Greater than 16 PCI clocks )

Snoop hit on modified cache line

Resource busy

Memory target locked

Reasons Target slow to complete a data phase which is neither the first nor

the final data phase ( more than 8 PCI clocks )

Targets don’t support burst mode

Memory target doesn’t understand address sequence

Transfer cross over target’s address boundary

Burst memory transfer crosses cache line boundary

Retry Retry

Reasons

( if the target cannot permit any data to be transferred )

Broken Target

I/O addressing error

Address phase parity error

Master abort on other side of PCI-to-PCI bridge

Target Abort Target Abort

Reasons

( if the target detects fatal error )

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Type A Disconnect

STOP#

Data Transfer

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Type B Disconnect

STOP#

Data Transfer

TRDY# asserted, STOP# asserted,

DEVSEL# asserted, IRDY# deasserted

TRDY# asserted, STOP# asserted,

DEVSEL# asserted, IRDY# asserted

Know in advance that the next data transfer takes more than 8 PCI clock

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Type C Disconnectwith IRDY# Asserted

STOP#

Data Transfer

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Type C Disconnectwithout IRDY# Asserted

STOP#

Data Transfer

TRDY# deasserted, STOP# asserted

DEVSEL# asserted

Current data transfer takes more than 8 PCI clock

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Retry ReceivedWith IRDY# Asserted

STOP#

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Retry ReceivedWithout IRDY# Asserted

STOP#

No Data Transfer

No Data Transfer


DEVSEL# assertedOccurs in the first data phase

DEVSEL#

FRAME#

CLK

IRDY#

TRDY#

1 2 3 4

Target Abort Example

STOP#

Master’s response to target abort:

• Generates an interrupt to alert is related

device to check its status.

• Generates SERR#


DEVSEL# deasserted

Shared Resource Acquisition

Shared Resource Acquisition

• LOCK#

Usage : Perform read/modify/write of a memory

semaphore as an atomic series to avoid

Synchronization Problem.

Solutions:

Bus LOCK : Permissible but not preferred

Resource LOCK: Preferred

Starting an Exclusive Access( Establishing LOCK#)

1 2 3 4 5CLK

FRAME#

LOCK#

AD

IRDY#

TRDY#

DEVSEL#

ADDRESS DATA

GNT#

LOCK# Mechanism Availability: Do not assert REQ# if LOCK# is currently asserted. If FRAME# and LOCK# are deasserted, assert its REQ#. The master continue to monitor LOCK# while waiting for GNT#. If LOCK# is sampled asserted, the master deasserted its REQ#. When the master samples bus idle ( FRAME# & IRDY# deasserted) and LOCK# deasserted, it has acquisition of the bus and of the LOCK#.



( Master < -> Target )




( Arbiter -> Target )

Accessing a Locked Agent : Retry

CLK

FRAME#

LOCK#

AD

IRDY#

TRDY#

STOP#

ADDRESS DATA

1 2 3 4 5

DEVSEL#

(driven low by master holding lock)

RetryGNT#

Continuing & Completing an Exclusive Access

CLK

FRAME#

LOCK#

AD

IRDY#

TRDY#

DEVSEL#

ADDRESS DATA

1 2 3 4 5

Continue

Release

GNT#

When Parity Error occurs:

Configuration status register : DETECTED PARITY ERROR

Configuration command register: PARITY ERROR RESPONSE

Assert PERR# Devices excluded from PERR# Requirement

Chipsets

Devices that don’t deal with OS/Application program or data

Error Detection and Handling

Parity on Read Transaction

TRDY#

DEVSEL#

FRAME#

CLK

PAR

PERR#

AD

1 2 3 4 5 6 87

Address 1st Data

C/BE# BUSCMD

3rd Data

2nd ByteEnables

3rd ByteEnables

1st ByteEnables

9

2nd Data

IRDY#

Add phase parity

1st Data parity 3rd Data Parity2nd Data

parity

1st phase PERR#

2nd phase PERR#

3rd phase PERR#earliest latest

Parity on Write Transaction

TRDY#

DEVSEL#

FRAME#

CLK

PAR

PERR#

AD

1 2 3 4 5 6 87

Address 1st Data

C/BE# BUSCMD

3rd Data

2nd ByteEnables 3rd Byte Enables1st Byte

Enables

9

2nd Data

IRDY#

Add phase parity

1st Data parity 3rd Data Parity2nd Data

parity

1st phase PERR#

2nd phase PERR#

3rd phase PERR#earliest latest

Configuration Related Issues

Configuration Address Space Format

Configuration Header Space

Device Specific Configuration

Registers

Byte Number

Dou

ble W

ord N

um

ber

00

1516

63

0123

Configuration Registers

00h

04h

08h

0Ch

10h

24h

28h

2Ch

30h

34h

38h

3Ch

0151631

BIST Cache LineSize

Base Address Registers

Cardbus CIS Pointer

Subsystem ID Subsystem Vendor ID

Expansion ROM Base Address

Reserved

Reserved

Max_Lat Min_Gnt Interrupt PinInterrupt

Line

Type 0 Configuration Space Header

Status

Required configuration registers

Latency Timer

Device ID Vendor ID

Command

Revision IDClass Code

Header Type

Command Register Bit Assignment

Reserved

Fast Back-to-Back Enable

DEVSEL Timing

Data Parity Reported

Signaled Target Abort

Received Target Abort

Received Master Abort

5 06789 4

Status Register

5 3 2 1 0

Reserved

678910

Fast Back-to-Back Enable

SERR# Enable

Wait Cycle Control

Parity Error Response

Palette Snoop EnableMemory Write and Invalidate Enable

Special Cycle Monitoring

Enable Mastering

Memory Access Enable

4

I/O Access Enable

15

15 14 13 12 11 10

66MHz-Capable

UDF Supported

Signaled System Error

Detected Parity Error

Class Code Register

Class Code Sub-Class Code Prog I/F

o78151623

Basic function More specific device subclass

Device specific programming interface

Eg. 06h 01h 00h

Bridge device PCI/ISA bridge

Header Type Register

067

Header Type

Configuration Header Format

0 = single function device

1 = multi function device

BIST Register

Completion CodeReserved

Start BIST

BIST Capable

7 6 5 4 3 0

04 3 2 1 0

Base Address31

PrefetchableType

Memory space indicator

Memory Base Address Register

Bits 2-1 00 Base register is 32 bits wide and can be mapped anywhere in the 32-bit memory space. 01 Base register is 32 bits wide must be mapped below 1M in memory space. 10 Base register is 64 bits wide and can be mapped anywhere in the 64-bit memory space. 11 Reserved

Bit 3 : set 1 if prefetchable, set 0 otherwise

Expansion ROM Base Address (Upper 21 bits) Reserved

Expansion ROM Register

01101131

Address decode enable

I/O Base Address Register

12 1 0

Base Address31

ReservedI/O space indicator

Configuration Transactions

• Usage: Access PCI configuration registers

A PCI device or host/PCI bridge require 64 doubleword of config. register

Each PCI function requires 64 doubleword of config. register

• Transaction type:

1. Type 0 configuration read or write transaction

2. Type 1 configuration read or write transaction

3. Memory mapped configuration mechanism ( PowerPC )

• Configuration mechanism:

1. Mechanism 1 ( Preferred)

2. Mechanism 2

Processor

System Memory

Bridge A

Host Bus

Expansion Bridge PCI Bus 0

Memory controller

Bridge B

Bridge D Bridge EPCI Device

PCI Bus 0PCI Device Bridge C

Bridge C

PCI bus 1 PCI bus 3 PCI bus5

PCI bus 2

PCI Bus 4

Expansion bus

PCI Bus 0

Peer Host/PCI Bridges

Type 0 Configuration Transaction

CONFIG_ADDRESS PORT: 0CF8 h - 0CFB h

CONFIG_DATA PORT : 0CFC h - 0CFF h

• Two 32 bit I/O ports are utilized at I/O address:

00DW

Number

Function

Number

Device

Number

Bus

Number Reserved

31 30 24 23 16 15 11 10 8 7 2 1 0

• Configuration Address Register at 0CF8h

1 = Enable Configuration space mapping 0CF8h0CF9h0CFAh0CFBh

• Contents of the AD bus during address phase

00DW

Number

Function

Number Reserved

31 30 11 10 8 7 2 1 0

0CF8h0CF9h0CFAh0CFBh

00DW

Number

Function

Number

Device

Number

Bus

Number Reserved

31 30 24 23 16 15 11 10 8 7 2 1 0

00DW

Number

Function

Number

31 30 16 15 11 10 8 7 2 1 0

Implementation of IDSEL

Decoder

……..

……..

Device Number

16 15 14 ………. 1 0

IDSEL

PCI Slot 1

IDSEL

PCI Slot 2

IDSEL

PCI Slot 3

IDSEL

PCI Slot 4....

TRDY#

GNT#

FRAME#

CLK

AD

1 2 3 4 5 6 87

Address

C/BE# Byte Enables

9

IRDY#

Config Read CMD

IDSEL#

Type 0 Configuration Read Access

Data

Processor write to config. address reg. at I/O port 0CF8

Host/PCI bridge

Bus num the same

YES

Type 0 configuration read or write at config. data port 0CFC

NO

Type 1 config. transaction

START

Pass PCI-to-PCI bridge

Target bus in the range

Bus num the same

YES

NOType 0 configuration read or write at config. data port 0CFC

Type 1 config. transaction

Configuration Mechanism 1

Interrupt Related Issues

Interrupt Signal Bonded To Value Hardwired In Pin RegisterDevice doesn’t generate interrupts 00h

INTA# pin 01hINTB# pin 02hINTC# pin 03hINTD# pin 04h

System IRQ Line Interrupt Routed to Value to be Written In Line Register

IRQ0 0d

IRQ1 1d

IRQ2 2d

IRQ15 15d

• Value to be Hardwired into Interrupt Pin Register

• Interrupt Line Register Values

INTA#

INTA#INTB#

INTA# INTB# INTC# INTD#

INTA#

INTA#

INTA#INTB#

INTA#

INTA#

INTB#

INTC#

INTD#IRQ8-15

Slave

8259

Master

8259

IRQ0-7

Programmable Interrupt router

Interrupt Design

Interrupt Chaining

Entry 1 ISR 1

Entry 2 ISR 2

INT B Entry 2ISR 2 with Entry 1 embedded

IRQ 1

Device 8259

INT A

INT B

IRQ 1

IRQ 2

If INT A and INT B both routed to IRQ1:

PCI Cache Support

• Snoop

SDONE : snoop done

SBO# : snoop backoff. ( HITM when assert.)• The non-cacheable transaction is regardless of SDONE and SBO#.

• Write Through : only use SDONE

• Memory Target Interpretation of Snoop Result Signal from Bridge

SDONE SBO# Description

0 X Standby

1 1 Clean snoop

1 0 Hit on a modified line

Wait States Inserted Until Snoop Completes

CLK1 2 3 4 5 6

FRAME#

AD

SBO#

IRDY#

TRDY#

SDONE

ADDRESS DATA

Hit to a Modified Line Followed by the Writeback

CLK1 2 3 4 5 6

FRAME#

AD

SBO#

IRDY#

TRDY#

SDONE

ADDRESS DATA-1

B CA

ADDRESS DATA-1 DATA-2

STOP#

writeback transaction

HITM CLEANHITMHITMHITM STANDBYSTANDBY

DEVSEL#

Expansion ROMs

Purpose: device-specific power-on self-test code

device-specific initialization code

device-specific interrupt routine

device-specific BIOS routine

device-specific code to be executed during the system boot process

ROM Detection:

Check if Expansion ROM base address

register exist

yes Read if the first two locations on base address register contain 55AAh

yes ROM exist

Code image copied to system DRAM

Execute initialization code

Code Image Format

PCI Expansion ROM Header Format

Offset Length Value Description

0h 1h 55h ROM Signature,byte 1

1h 1h AAh ROM Signature,byte 2

2h-17h 16h XX Reserved(processor architecture unique data)

18h-19h 2h XX Pointer to PCI Data Structure

Header

Data structure

Runtime Code

Initialization Code

(Can be discarded after execution)

Checksum

Unused space

Runtime Module within the Image

Unique Data Area in ROM Header

Offset Length Description

02h 1 Overall size of the image

03h-05h 3 Entry point for the initialization code

( POST performs a far call to initialize the device)

06h-17h 18 Reserved

Offset Length Description

0 h 4 Signature, the string “PCIR”

4 h 2 Vendor Identification

6 h 2 Device Identification

8 h 2 Pointer to Vital Product Data

Ah 2 PCI Data Structure Length

Ch 1 PCI Data Structure Revision

Dh 3 Class Code

10h 2 Image Length

12h 2 Revision Level of Code/Data

14h 1 Code Type

15h 1 Indicator (Bit 7, “1” last image)

16h 2 Reserved

PCI Data Structure Format

Introduction to PCI System Architecture. Contents: Introduction to PCI System PCI Bus Arbitration...

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