MELJUN CORTES Computer Organization Lecture Chapter6

8/13/2019 MELJUN CORTES Computer Organization Lecture Chapter6

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Chapter 6

Expansion Bus

MELJUN CORTES


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2007 The McGraw-Hill Companies, Inc. All rights reserved

OverviewIn this chapter, you will learn to

Identify the structure and function of the expansionbus

Explain classic system resources

Identify the modern expansion bus slots

Install expansion cards properly

Troubleshoot expansion card problems


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Structure and Function of theExpansion Bus

Historical/Conceptual


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Connections

Expansion slots connect to both the Northbridge andSouthbridge


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Two Crystals Two Speeds

All ICs are regulated by a clock crystalSystem crystal controls CPU, RAM, and chipset on the frontside bus

Expansion bus crystal controls boards on expansion bus


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PC Bus (8-bit ISA)

IBM XT had 8088 processor, 8-bit external data bus,and speed of 4.77 MHzExpansion bus ran at about 7 MHz (faster then thesystem bus)

AKA PC bus , XT bus , or ISA bus


7/40 2007 The McGraw-Hill Companies, Inc. All rights reserved

AT Bus (16-bit ISA)

AT bus is a 16-bit bus running at 8.33 MHz Added 8 bits to the end of the PC busPC/XT AKA 8-bit ISAPC/AT AKA 16-bit ISA


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Modern Expansion Bus

Essentials

CompTIA A+Essentials



False Starts Dead TodayMicrochannel Architecture (MCA)

MCA had a 32- bit bus to match the 386 CPUsexternal data bus with a speed of 12 MHz

Extended ISA (EISA)(EE-sah) was a 32-bit self-configuring expansionbus that was cheaper than MCA

Video Electronics Standards Association (VESA)Designed to solve the problems of speed andthroughput



PCIPeripheral Component Interconnect (PCI ) provides astronger, faster, and more flexible alternative to otherexpansion buses

The flexible design enables the PCI to coexist with otherbuses and scale up in speed and throughput

PCI devices are self-configuring (now known as plug and play)

PCI Special Interest Group (SIG)Defined I/O addresses and IRQs for most devicesUsed a sharable Interrupt Channel instead of IRQs



PCI

Fully implements DMA allowing PCI devices to transfer data amongthemselves

Divides its chipset duties between two chips

Northbridge (or PCI controller ) performs the classic functions andcontrols the PCI bus

Southbridge (PCI to ISA bridge or just PCI bridge ) acts as anintermediary between the PCI bus and the other bus



AGP

Accelerated Graphics Port (AGP)

PCI slot dedicated to video only

Brown-colored connector found on modern motherboards

More in Chapter 17



Other PCIPCI-X

Answers the need for speed

Mini-PCIDesigned to use low power and lie flatIdeal in laptop applications

PCI ExpressLanes of 2 GbpsDevices can use multiple lanes


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System Resources



System ResourcesExpansion cards and the CPU need some way tocommunicate

System resources help to define howcommunication occurs

I/O addressesIRQsDMA channelsMemory addresses

Rarely need to adjust today

Plug and play takes care of most of the work



I/O Addresses All devices must have an I/O address

Most devices use more than one I/O address (ora range of I/O addresses)

Devices must use different I/O addresses

The I/O memory wiresignals that a deviceis being addressed



I/O Address TerminologyWhen talking about I/O addresses, drop theleading zeroes (1F0not 01F0)

Every device gets a range of addresses

The first I/O address is base I/O address

Put an h on the end of the value to specify hex(1F0 h)

I/O addresses provide two-way communication(CPU to/from device)



23

1

8

Hexadecimal Compared to Binary

22 2 1 2 0

0 1 0

1010 Binary

Hexadecimal Table0 0 0 0 01 0 0 0 12 0 0 1 03 0 0 1 1

4 0 1 0 05 0 1 0 16 0 1 1 07 0 1 1 1

8 1 0 0 09 1 0 0 1A 1 0 1 0B 1 0 1 1

C 1 1 0 0D 1 1 0 1E 1 1 1 0F 1 1 1 1

4 2 1

Representing ten in binary and hex Binary 1 0 1 0 (1 eight and 1 two) Hexadecimal Ah (pronounced A hex



Hexadecimal Compared to Binary

How do you get to 10?0 1 2 3 4 5 6 7 8 9 10 Decimal

0 1 10 Binary0 1 2 3 4 5 6 7 8 9 A B C D E F 10 Hexadecimal

Counting to 10 Decimal 0, 1, 2 9, 10 Binary 0, 1, 10 Hexadecimal 0, 1, 2 E, F, 10



Interrupts

The CPU can initiate a conversation with any deviceat will

Any device may talk to the CPU, but how does adevice get the CPUs attention?

Devices use the interruption mechanism to gain theattention of the CPU by placing a voltage on aspecial wire called the INT (interrupt) wire



InterruptsMultiple devices, but only one INT

Devices use IRQs (interrupt requests)Separate IRQ for each device

I/O Advanced Programmable Interrupt Controller(IOAPIC) manages IRQs

IRQs numbered 0 through 23Used to be only 16

Open IRQs are unassignedPlug and Play assigns IRQs to new devices asneeded



COM and LPT PortsCommunication & Line Printer (LPT) portsIBM created standard preset combinations of IRQsand I/O addresses

The COM port and LPT port preset combinations:

COM1 03F8 IRQ4COM2 02F8 IRQ3COM3 03E8 IRQ4COM4 02E8 IRQ3LPT1 0378 IRQ7LPT2 0278 IRQ5


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(DMA)

Direct memory access (DMA) is the process of accessingmemory without using the CPUIt enables the system to run background applications withoutinterrupting the CPU


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Bus MasteringBus mastering devices use the DMA withoutaccessing the 8237 or CPU

Circuitry allows them to watch for other devices

accessing the external data busNo two devices can use the external data bus at thesame time

Extremely popular in hard drives All EIDE hard drives take advantage of busmastering

Floppy drives still use the old DMA


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Memory AddressesSome (not all) expansion cards need memoryaddresses

Two reasons for this:

1. May have onboard RAM that the CPU needs toaddress2. A few cards have onboard ROM

(adapter, option type; see Chapter 5)

RAM or ROM may steal memory addresses frommain system RAM

Memory addressing is fully automatic


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Installing Expansion Cards


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Steps to InstallingExpansion Cards

1. Knowledge

2. Physical installation

3. Device drivers

4. Verify


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Step 1: Knowledge1. Learn about the device by reading the

documentation

Do you have device drivers for your operating

system (Windows, Linux, etc.)

Does the device work with your operatingsystem?

Check the Windows Marketplacehttp://testedproducts.windowsmarketplace.com Devices on this list have been certified by Microsoft to workwith Windows
http://testedproducts.windowsmarketplace.com/http://testedproducts.windowsmarketplace.com/


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Step 2: Physical Installation

2. Install the cardHold the card on its edges dont touch connectorsor the components on the card

Insert at the proper angle

Use the connection screw,which helps to ground the card and

prevent card creep

Use proper ESD procedures


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Step 3: Device Drivers All devices require BIOS, which for expansioncards is almost always a device driver

Devices will come with device drivers on theinstallation CD

It is recommended that you get the latest driversfrom the manufacturers Web site

Which one first?Driver or device? Usually device firstIf USB or FireWire, driver first


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Unsigned DriversManufacturers submit drivers and devices toMicrosoft for testing

Once tested and verified, they are digitally signedUnsigned drivers give a warning

Drivers that haventbeen tested maystill work finedespite thescary message


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Installing the New DriverUse the CD that came with the device

May install extra unwanted programs

Use the Add Hardware Wizard in Control Panel


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Driver Rollback

Right-click the device inDevice Manager andchoose Properties, thenthe Driver tab

If you installed thewrong driver you can rollback to the previousdriver


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Step 4: Verify

Check the deviceproperties inDevice Manager toverify it is workingproperly


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Troubleshooting Expansion Cards

IT Technician

CompTIA A+Technician


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Device ManagerCheck for the device in Device Manager

Right-click My Computer | Properties | Hardwaretab | Device Manager

If the device does not show up in Device Manager

Run the Add/Remove Hardware Wizard in Control Panel

If it still doesnt show up, the device is damaged or is a legacydevice whose system resources are not configured properly


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Device Manager SymbolsBlack ! on a yellow circle

Device is missing, Windows doesntrecognize it, or a device driver problemDevice may still work

Red XDisabled device enable itDamaged device double-check workDevice will not work

Blue I on a white backgroundSystem resources were configured manuallyOnly seen on non-ACPI systemsInformation only device will work


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Device Manager

Device Manager allows youto see what resources arebeing used by your devices

Right-click My Computer |

Properties | Hardware tab |Device Manager button


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Documents

MELJUN CORTES Computer Organization Lecture Chapter6