Ebook Fundamentals of hardware and operating systems (Hardware Service Technician) - Part 2

Ebook Fundamentals of hardware and operating systems (Hardware Service Technician) - Part 2 presents the following content: Chapter 12 system protection; chapter 13 microprocessors; chapter 14 random access memory; chapter 15 motherboards; chapter 16 CMOS RAM; chapter 17 basic printer concepts; chapter 18 servicing printers; chapter 19 basic networking concepts; chapter 20 network media; chapter 21 internet connectivity.

C H A P T E R

System Protection

This chapter helps you to prepare for the Core

Hardware module of the A+ Certification examination

by covering the following objectives within the

“Domain 3.0: Preventive Maintenance” section

3.2 Identify various safety measures and procedures and when and how to use them.

Content may include the following:

• ESD (electrostatic discharge) precautions and procedures

• What ESD can do, how it may be apparent or den

hid-• Common ESD protection devices

• Situations that could present a danger or hazard

• Potential hazards and proper safety procedures relating to

Content may include the following:

• Special disposal procedures that comply with environmental guidelines

• Batteries

• CRTs

• Chemical solvents and cans

• MSDS (Material Safety Data Sheets)

Computer technicians should be aware of potential

environmental hazards and know how to prevent them

from becoming a problem Safety is an issue in every

profession Technicians should be aware of the potential

hazards associated with certain areas of the computer

and with certain types of peripheral equipment

Concerns for the world environment are at their highest

Many of the materials used in the construction of

com-puter-related equipment can be harmful Also, many of

the products used to service computer equipment can

have an adverse effect on the environment Therefore,

technicians should be aware of requirements associated

with the disposal of this equipment and these materials

PC repair personnel should be aware of the causes and

damaging effects of ESD so that they can prevent its

occurrence A good place to start checking for

environ-mental hazards is from the incoming power source The

following sections deal with power-line issues and

Avoiding Laser and Burn Hazards 465

To prepare for the Preventive Maintenance objective of the

Core Hardware exam:

➤ Use all the traditional study tools we’ve placed in the

chapter—Pay attention to the Objectives, Challenges and

end-of-chapter questions and use them to learn the rial

mate-➤ Use the pedagogy in this chapter to focus on the

exam-specific material—We’ve included lots of features

geared expressly to the A+ exam The Exam Tips tered throughout the chapter are placed there to point toknown exam-related materials The same is true of theembedded Challenge items

scat-➤ Key in on Exam Tips in the chapter—While reading

through the chapter, make sure to concentrate on the lowing test-related items:

fol-• Remember what the abbreviation ESD stands for.

Also, memorize the conditions that make ESD morelikely to occur Know when not to wear an antistaticwrist strap

• Know that high-voltage ratings do not make a ular contact point more dangerous than one with alower voltage; they have a higher current potential

partic-• Be aware of the effects that temperature cycling canhave on socket-mounted devices

• Remember that ESD is destructive and EMI is not

• Know that the best device for transporting computerequipment is the original manufacturer’s packaging,including the antistatic foam and bags used to packit

• Remember that toner cartridges from a laser printershould be recycled Also, be aware that the properdisposal method for batteries is to recycle them

• Be aware of the voltage levels that are presentinside a CRT cabinet Also, know that a long, flat-blade screwdriver is the proper tool to use for dis-charging the high-voltage anode of a cathode-raytube

• Know the best way to protect computer equipment in

an electrical storm

• Know the areas of the computer system that aredangerous for personnel and how to prevent injuryfrom these areas

• Remember the type of fire extinguisher that must beused with electrical systems, such as a PC

I NTRODUCTION

This chapter deals with environmental hazard conditions that candamage computer equipment or injure the user or technician Theseconditions include power-supply variations, electrostatic dischargeconditions, and potentially hazardous areas of the system

The chapter also describes procedures for properly disposing of puter equipment when it fails or reaches the end of its useful lifecycle

com-After completing the chapter, you should be able to describe differenttypes of typical power-supply variations and describe equipment thatcan be employed to minimize or remove these variations from thesystem

Likewise, you should be able to identify sources of ESD and specifyprecautions that can be taken to prevent static discharge Finally, youshould be able to identify potentially hazardous areas of the comput-

er and its peripherals

An electrostatic discharge (ESD) is the most severe form of

electro-magnetic interference (EMI) The human body can build up static

charges that range up to 25,000 volts These build-ups can dischargevery rapidly into an electrically grounded body or device Placing a25,000-volt surge through any electronic device is potentially damag-ing to it

At this point you may be wondering why the 25,000 volts associatedwith video monitors are deadly, whereas the 10,000 to 25,000 voltsassociated with ESD are not harmful to humans The reason is thedifference in current-delivering capabilities created by the voltage.Electronics instructors reiterate that it isn’t the voltage that will killyou; it’s the current (amperage)

The capability of the voltage associated with a video monitor to pushcurrent through your body is significant (several amps), whereas thesame capability associated with static is very low (micro-amps, or

Remember what the abbreviation ESD

stands for

thousandths of an amp) Therefore, it is possible for a lower voltage

device with a higher current rating (such as a 110 Vac power supply)

to be much more dangerous than a higher voltage source that has a

lower current-producing capability (such as static)

Static can easily discharge through digital computer equipment The

electronic devices that are used to construct digital equipment are

particularly susceptible to damage from ESD As a matter of fact,

ESD is the most damaging form of electrical interference associated

with digital equipment

The first step in avoiding ESD is being able to identify when and

why it occurs The most common causes of ESD are

➤ Low humidity (hot and dry conditions)

When people move, their clothes rub together and can produce large

amounts of electrostatic charge on their bodies Walking across

car-peting can create charges in excess of 1,000 volts Motors in

electri-cal devices, such as vacuum cleaners and refrigerators, also generate

high levels of ESD Some repair shops do not permit technicians to

use compressed air to blow dust out of keyboards and other computer

equipment because it has erroneously been linked to creating ESD

ESD is most likely to occur during periods of low humidity If the

relative humidity is below 50%, static charges can accumulate easily

ESD generally does not occur when the humidity is above 50%

Normal air-conditioning works by removing moisture from the

atmosphere Therefore, its presence can increase the potential for

ESD by lowering the humidity even further Anytime the static

charge reaches around 10,000 volts, it is likely to discharge to

grounded metal parts In many high-ESD situations, it is useful to

install a humidifier to raise the level of humidity in the work area

Know that high-voltage ratings do not make

a particular contact point more dangerousthan one with a lower voltage; they have ahigher current potential

Memorize the conditions that make ESDmore likely to occur

Be aware that compressed air can be used

to blow dust out of components and that itdoes not create ESD

C H A L L E N G E # 1

You have been asked to consult on the design of your company’s new repairfacility near Phoenix, Arizona In particular, management wants to know how toequip the work areas of the new facility You have not been to the site, but youknow that it is in a hot desert environment Also, the building will be air-condi-tioned How should you advise the management team about precautions thatshould be taken with the work area?

Refer to the “Challenge Solutions” section at the end of this chapter for the lution to the challenge

reso-MOS Handling Techniques

Metal oxide semiconductor (MOS) devices are sensitive to voltage

spikes and static electricity discharges For example, the level of

stat-ic electrstat-icity present on your body is high enough to destroy theinputs of a CMOS device if you touch its pins with your fingers.Professional service technicians employ a number of precautionarysteps when they are working on systems that may contain MOSdevices These technicians normally use a grounding strap, like theone depicted in Figure 12.1 This antistatic device may be placedaround the wrist or ankle to ground the technician to the systembeing worked on These straps release any static present on the tech-nician’s body and pass it harmlessly to ground potential

Antistatic wrist or ankle straps should never be worn while working

on higher voltage components, such as monitors and power-supplyunits Some technicians wrap a copper wire around their wrist orankle and connect it to the ground side of an outlet This practice isnot safe because the resistive feature of a true wrist strap is missing

As an alternative, most technicians’ work areas include antistaticmats made out of rubber or other antistatic materials that they stand

on while working on the equipment These mats are particularly ful in carpeted work areas because carpeting can be a major source ofESD buildup Some antistatic mats have ground connections thatshould be connected to the safety ground of an AC power outlet

Know when not to wear an antistatic wrist

strap

To avoid damaging static-sensitive devices, follow these procedures

to help minimize the chances of destructive static discharges:

➤ Before touching any components inside the system, touch an

exposed part of the chassis or the power-supply housing withyour finger, as illustrated in Figure 12.2 Grounding yourself inthis manner ensures that any static charge present on your body

is removed This technique should be used before handling acircuit board or component Of course, you should be awarethat this technique works safely only when the power cord isattached to a grounded power outlet The ground plug on astandard power cable is the best tool for overcoming ESDproblems

➤ Be aware that normal operating vibrations and temperature

cycling can degrade the electrical connections between ICs andsockets over time This gradual deterioration of electrical con-

tact between chips and sockets is referred to as chip creep.

F I G U R E 1 2 1

Typical antistatic devices.

➤ Use antistatic sprays or solutions on floors, carpets, desks, andcomputer equipment An antistatic spray or solution, appliedwith a soft cloth, is an effective deterrent to static.

➤ Install static-free carpeting in the work area You can alsoinstall an antistatic floor mat as well Install a conductive table-top to carry away static from the work area Use antistatic mats

on the work surface

➤ Use a room humidifier to keep the humidity level above 50%

in the work area

Understanding Grounds

The term ground is often a source of confusion for the novice

because it actually encompasses a collection of terms Generically,

F I G U R E 1 2 2

Discharging through the power-supply unit.

Be aware of the effects that temperature

cycling can have on socket-mounted

devices

ground is simply any point from which electrical measurements are

referenced However, the original definition of ground actually

referred to the ground This ground is called earth ground.

The movement of the electrical current along a conductor requires a

path for the current to return to its source In early telegraph systems

and even modern power transmission systems, the earth provides a

return path and, hypothetically, produces an electrical

reference point of absolute zero This type of ground is shown in

Figure 12.3

F I G U R E 1 2 3

Power transmission system.

Grounding is an important aspect of limiting EMI in computer

sys-tems Left unchecked, EMI can distort images on the video display,

interfere with commercial communication equipment (such as radios

and televisions), and corrupt data on floppy disks In addition, EMI

can cause signal deterioration and loss due to improper cable routing

If a signal cable is bundled with a power cord, for example, radiation

from the power cord may be induced into the signal cable, affecting

the signals that pass through it Good grounding routes the induced

EMI signals away from logic circuitry and toward ground potential,

Remember that ESD is destructive andEMI is not

preventing it from disrupting normal operations Unlike ESD, which

is destructive, the effects of EMI can be corrected without damage.Because a computer system is connected to an actual earth ground, itshould always be turned off and disconnected from the wall outletduring electrical storms This includes the computer and all itsperipherals The electrical pathway through the computer equipmentcan attract lightning on its way to earth ground The extremely highelectrical potential of a lightning strike is more than any computercan withstand

The best storage option for most computer equipment is the originalmanufacturer’s box These boxes are designed specifically to storeand transport the device safely They include form-fitting protectivefoam to protect the device from shock hazards The device is normal-

ly wrapped in a protective antistatic bag or wrapper to defeat theeffects of ESD

Monitors, printers, scanners, and other peripheral equipment should

be stored in their original boxes, using their original packing foamand protective storage bag The contours of the packing foam forthese devices are not generally compatible from model to model ordevice to device This is also the best packaging for transportingthese devices If the original boxes and packing materials are notavailable, make sure to use sturdy cartons and cushion the equipmentwell on all sides before shipping

When you are storing batteries, such as spares for a notebook puter, there are two scenarios to consider: short-term storage (fewerthan 30 days) and long-term storage (more than 30 days) If you plan

com-on storing a battery for fewer than 30 days, you should fully charge itand store it in a cool, dry place Some references suggest refrigerat-ing charged batteries during storage to increase the time they willhold their charge In these cases, allow the battery to return to roomtemperature and dry it thoroughly before reinstalling it On the otherhand, if the battery will be stored for a longer time, fully dischargethe battery before storing it

Know that the best device for transporting

computer equipment is the original

manu-facturer’s packaging, including the antistatic

foam and bags used to pack it

D ISPOSAL P ROCEDURES

Most computer components contain some level of hazardous

sub-stances Printed circuit boards consist of plastics, precious metals,

fiberglass, arsenic, silicon, gallium, and lead CRTs contain glass,

metal, plastics, lead, barium, and rare earth metals Batteries from

portable systems can contain lead, cadmium, lithium, alkaline

man-ganese, and mercury

Although all these materials can be classified as hazardous materials,

so far there are no widespread regulations when it comes to placing

them in the landfill Conversely, local regulations concerning

accept-able disposal methods for computer-related components should

always be checked before disposing of any electronic equipment

Laser printer toner cartridges can be refilled and recycled However,

you should use such cartridges only for draft-mode operations where

very good resolution is not required Ink cartridges from ink-jet

print-ers can also be refilled and reused Like laser cartridges, they can be

very messy to refill and often do not function as well as new

car-tridges do In many cases, the product’s manufacturer has a policy of

accepting spent cartridges

For both batteries and cartridges, the desired method of disposal is

recycling Finding a drop site that handles recycling of these products

should not be too difficult On the other hand, even nonhazardous

Subtitle-D dumpsites can handle the hardware components if

neces-sary Subtitle-D dumpsites are nonhazardous, solid waste dumpsites

that have been designed to meet EPA standards set for this

classifica-tion These sites are designed to hold hazardous materials safely

All hazardous materials are required to have Material Safety Data

Sheets (MSDS) that accompany them when they change hands These

sheets are also required to be available in areas where hazardous

materials are stored and commonly used

These information sheets must be provided by the hazardous material

supplier Likewise, if you supply hazardous material to a third party,

you must also supply the MSDS for the material These sheets

inform workers and management about hazards associated with the

product and ways to handle it safely They also provide instructions

about what to do if an accident occurs involving the material

A VOIDING H IGH -V OLTAGE H AZARDS

In most IBM-compatibles, there are only two potentially dangerousareas for high-voltage hazards These areas include inside the CRTdisplay and inside the power-supply unit Both of these areas containelectrical voltage levels that are lethal; however, they reside in self-contained units, and you will normally not be required to open eitherunit

As a matter of fact, you should never enter the interior of a CRT inet unless you have been trained specifically to work with this type

cab-of equipment The tube itself is dangerous if accidentally cracked Inaddition, extremely high voltage levels (in excess of 25,000 volts)may be present inside the CRT housing, even up to a year after elec-trical power has been removed from the unit

In repair situations, the high-voltage charge associated with video plays must be discharged This is accomplished by creating a pathfrom the tube’s high-voltage anode to the chassis With the monitorunplugged from the commercial power outlet, clip one end of an insu-lated jumper wire to the chassis ground of the frame Clip the otherend to a long, flat-blade screwdriver that has a well-insulated handle.While touching only the insulated handle of the screwdriver, slide theblade of the screwdriver under the rubber cup of the anode and makecontact with its metal connection This action should bleed off thehigh-voltage charge to ground Continue the contact for several sec-onds to ensure that the voltage has been fully discharged

dis-Never open the power-supply unit Some portions of the circuitryinside the power supply carry extremely high voltage levels and havevery high current capabilities Generally, no open shock hazards arepresent inside the system unit However, you should not reach insidethe computer while power is applied to the unit Jewelry and othermetallic objects pose an electrical threat, even with the relatively lowvoltage present in the system unit

Do not defeat the safety feature of three-prong power plugs by usingtwo-prong adapters The equipment ground of a power cord shouldnever be defeated or removed This plug connects the computer chas-sis to an earth ground through the power system This provides a ref-erence point for all the system’s devices to operate from and suppliesprotection for personnel from electrical shock In defeating theground plug, a very important level of protection is removed from

Be aware of the voltage levels that are

pre-sent inside a CRT cabinet

Be aware that a long, flat-blade screwdriver

is the proper tool to use for discharging the

high-voltage anode of a cathode-ray tube

the equipment You should remove all power cords associated with

the computer and its peripherals from the power outlet during

thun-derstorms

Periodically examine the power cords of the computer and

peripher-als for cracked or damaged insulation Replace worn or damaged

power cords promptly Never allow anything to rest on a power cord

Run power cords and connecting cables safely out of the way so that

they don’t become trip, or catch, hazards

Don’t apply liquid or aerosol cleaners directly to computer equipment

Spray cleaners on a cloth and then apply the cloth to the equipment

Freon-propelled sprays should not be used on computer equipment

because they can produce destructive electrostatic charges

Laser printers contain many hazardous areas The laser light can be

very damaging to the human eye In addition, there are multiple

high-voltage areas in the typical laser printer and a high-temperature

area to contend with as well

Sometimes you need to bypass safety interlocks to isolate problems

When doing so, observe proper precautions, such as avoiding the

laser light, being aware of the high temperatures in the fuser area,

and following proper procedures with the high-voltage areas of the

unit The laser light is a hazard to eyesight, the fuser area is a burn

hazard, and the power supplies are shock hazards

Another potential burn hazard is the printhead mechanism of a

dot-matrix printer During normal operation, it can become hot enough to

be a burn hazard if touched

Because computers have the potential to produce these types of

injuries, it is good practice to have a well-stocked first-aid kit in the

work area In addition, a Class-C fire extinguisher should be on hand

Class-C extinguishers are the type specified for use around electrical

equipment You can probably imagine the consequences of applying

a water-based fire extinguisher to a fire with live electrical

equip-ment around The ratings for class, or classes, of the fire extinguisher

are typically marked on its side

to prevent injury from these areas

Remember the type of fire extinguisher thatmust be used with electrical systems, such

as a PC

This chapter focused on environmental hazards that affect the tion of computer equipment The initial sections of the chapter dealtwith problems caused by fluctuations in the computer’s incomingpower line Different types of universal power supplies were dis-cussed, along with other power-line conditioning devices

opera-The next section of the chapter discussed proper storage methods fortypical computer components

Potentially hazardous areas of the computer and its peripherals werepresented in the third major section of the chapter Although not anintrinsically unsafe environment, some areas of a computer systemcan be harmful if approached unawares

Cleaning materials and disposal of old and defective equipment wereaddressed in the next section of the chapter MSDS records were alsointroduced

The final section of the chapter described the danger and causes ofelectrostatic discharges and provided information about how to elimi-nate them

At this point, review the objectives listed at the beginning of thechapter to be certain that you understand the information associatedwith each one and that you can perform each item listed there.Afterward, answer the review questions that follow to verify yourknowledge of the information

A P P L Y Y O U R K N O W L E D G E

Review Questions

1 In terms of maintenance issues, how are the

effects of ESD and EMI different?

A ESD is not destructive, whereas EMI can bevery destructive

B EMI is not destructive, whereas ESD can bevery destructive

C EMI improves system efficiency, whereasESD can be very destructive

D ESD improves system efficiency, whereasEMI can be very destructive

2 Which voltage level is more dangerous: 110 Vac

at 5 amps or 25,000 Vdc at 5 microamperes?

A Neither is particularly dangerous

B Five amps is much more dangerous than 5microamperes

C Both are extremely dangerous

D Twenty-five thousand volts is much more gerous than 110 volts

dan-3 Damaging electrostatic discharge is most likely to

occur when _

A working around rubber mats

B using test instruments on a system

C the humidity is low

D you accidentally get too close to the supply unit while it is operating

power-4 You should not wear a wrist grounding strap

when _

A replacing an adapter card

B repairing a motherboard

C repairing a CRT

D adding or replacing RAM

5 _ is the gradual deterioration of the electricalconnection between the pins of an IC and itssocket

C a sturdy carton filled with Styrofoam peanuts

D the original packaging

7 What is the recommended method for handling anempty toner cartridge?

A Recycle it

B Throw it in the trash

C Burn it in a certified incinerator

D Turn it in to a licensed computer retailer

8 What is the recommended method for handling adead battery?

A Recycle it

B Throw it in the trash

C Burn it in a certified incinerator

D Recharge it

11 The local weather report indicates that an

electri-cal storm with severe winds is likely to occur in

your area overnight What reasonable precautions

should you take to protect your computers?

A Monitor the computers until the storm

passes

B Plug the computers into a surge protector

C Turn off the computers

D Unplug the computers

12 What type of fire extinguisher should be used

13 The of dot-matrix printers generates a

great deal of heat and can be a burn hazard when

you are working on these units

mini-A surge protector

B terrycloth towel

C wrist strap

D screwdriver

Answers and Explanations

1 B Electrostatic discharge (ESD) can send severe

overvoltages into electrical equipment that havethe potential to cause permanent damage to sensi-tive electronic components ElectroMagneticInterference (EMI) occurs when strong electro-magnetic fields distort signals within the system,causing a partial or complete system crash UnlikeESD, which is destructive, the effects of EMI can

be corrected without damage

2 B It isn’t the voltage that will kill you, it’s the

current (amperage) The capability of the voltageassociated with a video monitor to push current

3 C ESD is most likely to occur during periods of

low humidity If the relative humidity is below50%, static charges can accumulate easily ESDgenerally does not occur when the humidity isabove 50% In many high-ESD situations, it isuseful to install a humidifier to raise the level ofhumidity in the work area

4 C A wrist strap is a conductor designed to carry

electrical charges away from your body In voltage environments such as those found inside apower-supply unit or a monitor, however, thissafety device becomes a potential path for electro-cution

high-5 C Chip creep is the degradation of the contact

between an IC and its socket, and it occursbecause of the effects of temperature cycling onthe IC pins and the socket contacts

6 D The best storage option for most computer

equipment is the original manufacturer’s box

7 A Laser printer toner cartridges can be refilled

and recycled

8 A For both batteries and cartridges, the desired

method of disposal is recycling

9 C Extremely high voltage levels (in excess of

25,000 volts) may be present inside the CRThousing, even up to a year after electrical powerhas been removed from the unit

10 D In repair situations, the high-voltage charge

asso-ciated with video displays must be discharged This

is accomplished by creating a path from the tube’shigh-voltage anode to the chassis With the monitorunplugged from the commercial power outlet, clipone end of an insulated jumper wire to the chassisground of the frame Clip the other end to a long,flat-blade screwdriver that has a well-insulated han-dle While touching only the insulated handle of thescrewdriver, slide the blade of the screwdriverunder the rubber cup of the anode and make contactwith its metal connection This action should bleedoff the high-voltage charge to ground Continue thecontact for several seconds to ensure that the volt-age has been fully discharged

11 D For complete protection from potential

light-ning strikes, you should completely disconnectthe computers from the commercial power source(unplug them from the outlets) so that there is nopath for the lightning to follow

12 C A Class-C (CO2) fire extinguisher should

always be on hand Class-C extinguishers are thetype specified for use around electrical equip-ment

13 C To exchange the printhead assembly, make

sure that it is cool enough to be handled Theseunits can get hot enough to cause a serious burn

14 A Laser printers can be a source of electrocution,

eye damage (from the laser), and burns (from thefuser assembly) The laser printer tends to haveseveral high-voltage and high-temperature hazardsinside it To get the laser printer into a positionwhere you can observe its operation, you need todefeat some interlock sensors This action placesyou in potential contact with the high-voltage,high-temperature areas in the printer Take greatcare when working inside a laser printer

A P P L Y Y O U R K N O W L E D G E

15 C Professional service technicians employ a

number of precautionary steps when they are

working on systems that might contain MOS

devices These technicians normally use a

ground-ing strap These antistatic devices can be placed

around the wrist or ankle to ground the technician

to the system being worked on These straps

release any static present on the technician’s body

and pass it harmlessly to ground potential

Challenge Solutions

1 The facility should be equipped with a humidifiersystem to overcome the effects of the hot, dry cli-mate and the air-conditioning It should also haveantistatic floor mats, antistatic desk mats, andantistatic wrist straps for the technicians

1 How Surge Suppression Works

5 ESDhttp://www.netlabs.net/hp/echase/

6 Handling MOS Deviceshttp://www.claremicronix.com/pdfs/

tone_signaling/AN-MOS-R1.pdf

7 Groundshttp://www.amasci.com/emotor/ground.html

Suggested Readings and Resources

C H A P T E R

Microprocessors

This chapter helps you to prepare for the Core

Hardware module of the A+ Certification examination

by covering the following objectives within the

“Domain 4.0: Motherboard/Processors/Memory”

section

4.1 Distinguish between the popular CPU chips in terms of their basic characteristics.

Content may include the following:

• Popular CPU chips (Pentium class compatible)

• Voltage

• Speeds (actual versus advertised)

• Cache level I, II, III

• Sockets/slots

• Voltage regulator modules

Computer technicians are often asked to upgrade

exist-ing systems with new devices, such as the

microproces-sor Therefore, every technician should be aware of the

characteristics of possible CPU upgrades and be able to

determine whether a particular upgrade is physically

possible and worthwhile

Successful technicians must be aware of the

capabili-ties of the different microprocessors available for use in

a system They must know what impact placing a

par-ticular microprocessor in an existing system can have

on its operation They must also be able to identify the

type of processor being used and the system setting

necessary to maximize its operation

Introduction 474

To prepare for the Motherboard/Processors/ Memory objective

of the Core Hardware exam:

➤ Use all the traditional study tools we’ve placed in the

chapter—Pay attention to the Objectives, Challenges and

end-of-chapter questions and use them to learn the rial

mate-➤ Use the pedagogy in this chapter to focus on the

exam-specific material—We’ve included lots of features

geared expressly to the A+ exam The Exam Tips tered throughout the chapter are placed there to point toknown exam-related materials The same is true of theembedded Challenge items

scat-➤ Key in on Exam Tips in the chapter—While reading

through the chapter, make sure to concentrate on the lowing test-related items:

fol-• Know which microprocessor employs half-speedcache Remember which components Intel included

in the SEC cartridge

• Be able to state the differences between Pentium IIand Pentium III processors

• Memorize which processors can be used with Slot 1and Socket 370 connections Also know whichprocessors can be used in Slot-A

• Be aware of how older systems determine what type

of microprocessor is installed and what its ties are

capabili-• Know why a processor would show an incorrectspeed rating

I NTRODUCTION

The system board is the main component of any personal computersystem This chapter examines the system board’s main component:

the microprocessor These devices establish the basic capabilities of

the entire computer system, so the technician must be aware of how

to install, upgrade, and maintain them so that they provide optimumperformance for the system

The chapter describes the different Pentium class microprocessors interms of their capabilities, speeds, and physical appearance

The discussion goes on to describe typical socket specifications thathave been developed for installing different microprocessors on sys-tem boards

Finally, the chapter deals with configuring system boards to workwith different microprocessor types

After completing this chapter, you should be able to describe thebasic characteristics and attributes associated with popular micro-processors You should also be able to perform microprocessor instal-lations and configurations, as well as to identify possible options forconducting microprocessor upgrades

When IBM was designing the first PC, it chose the Intel 8088 processor and its supporting chipset as the standard CPU for itsdesign This was a natural decision because one of IBM’s majorcompetitors (Apple) was using Motorola microprocessors for itsdesigns The choice to use the Intel microprocessor still has animpact on the design of PC-compatible systems As a matter of fact,the microprocessors used in the vast majority of all PC-compatiblemicrocomputers include the Intel 8088/86, 80286, 80386, 80486, andPentium (80586 and 80686) devices

micro-The original Pentium processor was a 32/64-bit design housed in aCeramic Pin Grid Array package Its registers and floating-point sec-tions were identical to those of its predecessor, the 80486 It had a64-bit data bus that enabled it to handle Quad Word data transfers It

also contained two separate 8KB caches, compared to only one in the

80486 One cache was used for instructions or code, and the other

was used for data

This original Pentium architecture has appeared in three generations

The first generation, code-named the P5, came in a 273-pin PGA

package and operated at 60 or 66MHz speeds It used a single +5V

(DC) operating voltage, which caused it to consume large amounts of

power and generate large amounts of heat It generated so much heat

during normal operation that an additional CPU cooling fan was

required

The second generation of Pentiums, referred to as P54Cs, came in a

296-pin Staggered Pin Grid Array (SPGA) package and operated at

75, 90, 100, 120, 133, 150, and 166MHz in different versions For

these devices, Intel reduced the power-supply voltage level to +3.3V

(DC) to consume less power and provide faster operating speeds

Reducing the power-supply level in effect moves the processor’s

high- and low-logic levels closer together, requiring less time to

switch back and forth between them The SPGA packaging made the

second generation of Pentium devices incompatible with the

first-generation system boards

The second-generation devices also employed internal clock

multipli-ers to increase performance In this scenario, the system’s buses run

at the same speed as the clock signal introduced to the

microproces-sor; however, the internal clock multiplier causes the microprocessor

to operate internally at some multiple of the external clock speed

(that is, a Pentium operating from a 50MHz external clock and using

a 2x internal multiplier is actually running internally at 100MHz)

The third generation of Pentium designs, designated as P55C, uses

the 296-pin SPGA arrangement This package adheres to the 321-pin

Socket-7 specification designed by Intel The P55C has been

pro-duced in versions that operate at 166, 180, 200, and 233MHz This

generation of Pentium devices operates at voltages below the +3.3V

level established in the second generation of devices The P55C is

known as the Pentium MMX (Multimedia Extension) processor.

Figure 13.1 shows the pin arrangements for PGA and SPGA devices

Notice the uniformity of the PGA rows and columns versus the

stag-ger in the rows and columns of the SPGA device

A DVANCED P ENTIUM A RCHITECTURES

Intel has continued to improve its Pentium line of microprocessors byintroducing additional specifications, including the Pentium MMX,Pentium Pro, Pentium II, Pentium III, and Pentium 4 processors Atthe same time, Intel’s competitors have developed clone designs thatequal or surpass the capabilities of the Intel

instruc-233MHz versions and used a 321-pin, SPGA Socket-7 format It

required two separate operating voltages One source was used todrive the Pentium processor core; the other was used to power theprocessor’s I/O pins New external input signals were added to thePentium architecture in the MMX versions This was done to imple-ment the VRM and internal clock multiplier functions that have con-tinued through the advanced Pentium designs following the MMXversion

F I G U R E 1 3 1

PGA and SPGA arrangements.

Pentium Pro

Intel departed from simply increasing the speed of its Pentium

processor line by introducing the Pentium Pro processor Although

compatible with all the software previously written for the Intel

processor line, the Pentium Pro was optimized to run 32-bit software

However, the Pentium Pro did not remain pin-compatible with the

previous Pentium processors Instead, Intel adopted a 2.46”by

2.66”, 387-pin PGA configuration to house a Pentium Pro processor

core and an onboard 256KB (or 512KB) L2 cache; the Pentium Pro

also employs a 60 or 66MHz system bus The L2 cache complements

the 16KB L1 cache in the Pentium core Figure 13.2 illustrates this

arrangement Notice that although the two components are on the

same PGA device, they are not integrated into the same IC The unit

is covered with a gold-plated copper/tungsten heat spreader

The L2 onboard cache stores the most frequently used data not found

F I G U R E 1 3 2

The Pentium Pro microprocessor.

in the processor’s internal L1 cache as close to the processor core as

it can be without being integrated directly into the IC A

high-band-width cache bus connects the processor and cache unit together The

bus (0.5”in length) allows the processor and external cache to

com-municate at a rate of 1.2GBps

The Pentium Pro was designed to be used in typical

single-microprocessor applications or in multiprocessor environments, such

as high-speed, high-volume file servers and workstations Several

dual-processor system boards have been designed for twin Pentium

Pro processors These boards are created with two Pentium Pro

sock-ets so that they can operate with either a single processor or with

dual processors When dual processors are installed, logic circuitry inthe Pentium Pro’s core manages the requests for access to the sys-tem’s memory and 64-bit buses.

Pentium II

Intel radically changed the form factor of the Pentium processors by

housing the Pentium II processor in a new Single-Edge Contact

(SEC) cartridge, depicted in Figure 13.3 This cartridge uses a special

retention mechanism built into the system board to hold the device inplace

F I G U R E 1 3 3

The Pentium II cartridge processor.

The proprietary 242-contact socket design is referred to as the Slot 1

specification and was designed to enable the microprocessor to ate at bus speeds in excess of 300MHz

oper-The cartridge also requires a special Fan Heat Sink (FHS) module

and fan Like the SEC cartridge, the FHS module requires specialsupport mechanisms to hold it in place The fan draws power from aspecial power connector on the system board or from one of the sys-tem’s options power connectors

Inside the cartridge, the processor and related components are

mount-ed on a substrate material The components consist of the Pentium II

processor core, a tag RAM, and an L2 burst SRAM Tag RAM is

used to track the attributes (read, modified, and so on) of data stored

in the cache memory

The Pentium II includes all the multimedia enhancements from the

MMX processor and retains the power of the Pentium Pro’s dynamic

execution and 512KB L2 cache features; it also employs a 66 or

100MHz system bus The L1 cache is increased to 32KB, whereas

the L2 cache operates with a half-speed bus

Figure 13.4 depicts the contents of the Pentium II cartridge

Know which microprocessor employs speed cache

half-Remember which components Intel

includ-ed in the SEC cartridge

F I G U R E 1 3 4

Inside the Pentium II cartridge.

A second cartridge type, called the Single-Edged Processor Package

(SEPP), has been developed for use with the Slot 1 design In this

design, the boxed processor is not completely covered by the plastic

housing as it is in the SECC design Instead, the SEPP circuit board

is accessible from the backside

Pentium III

Intel followed the Pentium II processor with an improved low-cost

design it called the Pentium Celeron The first version of this line of

processors was named the Covington This processor was built

around a Pentium II core without a built-in cache Later, the Celeron

Mendocino version featured a 66MHz bus speed and only 128KB of

L2 cache Initially, this version was packaged in the SEC cartridge

You can upload processor update informationinto the BIOS that has ApplicationProgramming Interface (API) capabilities builtinto it You can do this to modify the operation

of Pentium Pro and Pentium II/III/4 sors The microprocessor manufacturer placesupdate information on its Web site that can bedownloaded by customers The user transfersthe update information from the update media

proces-to the system’s BIOS via the API routine If theupdated data is relevant (as indicated bychecking its processor stepping code), the APIwrites the updated microcode into the BIOS.This information will, in turn, be loaded intothe processor each time the system is booted

Intel quickly followed the Celeron release with a new Slot

1–compat-ible design it called the Pentium III The original Pentium III

proces-sor (code-named Katmai) was designed around the Pentium II core,but increased the L2 cache size to 512KB It also increased the speed

of the processor to 600MHz, including a 100MHz front-side bus

(FSB) speed.

Later versions of the Pentium III and Celeron processors were oped for the Intel Socket 370 specification This design returned to a370-pin, ZIF socket/SPGA package arrangement, depicted in Figure13.5

devel-F I G U R E 1 3 5

Socket 370/Celeron.

The first pin grid array versions of the Pentium III and Celeron

processors conformed to a standard called the Plastic Pin Grid Array

(PPGA) 370 specification Intel repackaged its processors into a PGA

package to fit this specification The PPGA design was introduced toproduce inexpensive, moderate-performance Pentium systems Thedesign topped out at 533MHz with a 66MHz bus speed

Intel upgraded the Socket 370 specification by introducing a variation

called the Flip Chip Pin Grid Array (FC-PGA) 370 design Intel

made small modifications to the wiring of the socket to

accommo-date the Pentium III processor design In addition, the company

employed a new 0.18 micron IC manufacturing technology to

pro-duce faster processor speeds (up to 1.12GHz) and front-side bus

speeds (100MHz and 133MHz) However, the new design provides

only 256KB of L2 cache

Pentium III and Celeron processors designed with the 0.18 micron

technology are referred to as Coppermine and Coppermine 128

processors, respectively (The L2 cache in the Coppermine 128 is

only 128KB.) Further developments of the Coppermine versions,

referred to as Tualatin, employed 0.13 micron IC technology to

achieve 1.4GHz operating speeds with increased cache sizes (256KB

or 512KB)

Xeon

Intel has produced three special versions of the Pentium III that are

collectively named the Pentium Xeon, as shown in Figure 13.6.

These processors are designed to work with an edge-connector–based

Slot 2 specification that Intel has produced to extend the Slot 1,

boxed-processor scheme to a 330-contact design Each version

fea-tures a different level of L2 cache (512KB, 1MB, 2MB)

The Xeon designs were produced to fill different, high-end server

needs The Xeon processor functions at speeds up to 866MHz and is

built on the 0.18-micron process technology The processor allows

for highly scalable server solutions that support up to 32 processors

Pentium 4

Late in 2000, Intel released its newest Pentium version called the

Williamette 423, or Pentium 4, microprocessor However, the

Pentium 4 is not a continuation of the Pentium design It is actually a

new design (IA-32 NetBurst architecture) based on 0.18 micron IC

construction technology It employs a modified Socket 370 PGA

design that uses 423 pins and boasts operating speeds up to 2.0GHz

The internal processor bus has been increased from 64 to 128 bits

and operates at up to 400MHz Newer 0.13 micron versions are

code-named Northwood and operate at speeds up to 3.06GHz using a

133MHz front-side bus clock, to deliver 533MHz front-side bus

speeds The latest version of the Pentium (named Prescott) is

Be able to state the differences betweenPentium II and Pentium III processors

designed to run at 3.2 and 3.6GHz with an 800MHz front-side busspeed These newer Pentium 4 designs employ an improved 478-pinversion of the chip.

F I G U R E 1 3 6

The Xeon processor.

In addition to the new front-side bus size, the Pentium 4 features new

Williamette Processor New Instructions (WPNI) in its instruction set.

The L1 cache size has been reduced from 16KB in the Pentium III to8KB for the Pentium 4 The L2 cache is 256KB and can handle trans-fers on every clock cycle

The operating voltage level for the Pentium 4 core is 1.7Vdc To sipate the 55 watts of power (heat) that the microprocessor generates

dis-at 1.5GHz, the case incorpordis-ates a metal cap thdis-at acts as a built-inheat sink Firm contact must be maintained between the microproces-sor’s case and its built-in heat sink feature

Itanium Processors

The Intel Itanium processor, depicted in Figure 13.7, provides a new

architecture specifically for servers It maximizes server performance

through special processing techniques Intel refers to as Explicitly

Parallel Instruction Computing (EPIC) Although the Itanium was

orig-inally intended primarily for the high-end server market, Microsoft has

included support for Itanium processors in its Windows XP Professional

operating system, indicating that it expects to see these processors wind

up in high-end client computer applications

F I G U R E 1 3 7

The Itanium processor.

The Itanium processor design features a new three-level, onboard

cache system The L1 cache size is 32KB operating fully pipelined,

whereas the L2 cache size is 96KB and the new L3 cache is available

in two sizes: 2MB and 4MB The cartridge’s edge connector

specifi-cation provides separate voltage levels for the processor and cache

devices to improve signal integrity

Because Itanium processors are designed to be available 100% of the

time, they tend to be very expensive—often more expensive than the

complete network operating system that they are running However,

the cost of this processor is nothing compared to the cost of most

online businesses going down for just one hour

Table 13.1 summarizes the characteristics of the Intel Pentium

micro-processors

T A B L E 1 3 1

C H A R A C T E R I S T I C S O F T H E I N T E L P E N T I U M

M I C R O P R O C E S S O R S

Advanced Micro Devices (AMD) offers several clone

microproces-sors: the 5x86 (X5), 586 (K5), K6, K6PLUS-3D, and K7 processors The X5 offers operational and pin compatibility with theDX4 Its performance is equal to that of the Pentium and MMXprocessors The K5 processor is compatible with the Pentium, andthe K6 is compatible with the MMX Both the K5 and K6 models areSocket-7 compatible, enabling them to be used in conventionalPentium and Pentium MMX system board designs (with some smallmodifications) The K6 employs an extended 64KB L1 cache thatdoubles the internal cache size of the Pentium II

micro-The K6PLUS-3D is operationally and performance compatible withthe Pentium Pro, and the K7 is operationally and performance com-patible with the Pentium II However, neither of these units has a pin-out compatibility with another processor

AMD continues to produce clone versions of Pentium processors Insome cases, the functions and performance of the AMD devices gobeyond those of the Intel design they are cloning Two notable AMDPentium clone processors are the Athlon and the Duron

The Athlon is a Pentium III clone processor It is available in a Slot 1

cartridge clone, called the Slot-A specification Figure 13.8 depictsthe cartridge version of the Athlon processor along with a Slot-Aconnector

The Athlon is also available in a proprietary SPGA Socket-A designthat mimics the Intel Socket 370 specification The Socket-A specifi-cation employs a 462-pin ZIF socket and is supported only by twoavailable chipsets

Three versions of the Athlon processor have been introduced so far.

The first version was the K7 version that ran between 500MHz and

700MHz, provided a 128KB L1 cache and a 512KB L2 cache,

employed a 100MHz system bus, and used Slot-A

Subsequent Athlon versions have included the K75 and Thunderbird

versions Both versions are constructed using 0.18 micron

manufac-turing technology The K75 processors run between 750MHz and

1GHz Like the K7 version, the K75 provides a 128KB L1 cache and

a 512KB L2 cache, and employs a 100MHz system bus The

Thunderbird version runs between 750MHz and 1.2GHz, provides a

128KB L1 cache and a 256KB L2 cache, employs a 133MHz system

bus, and features a Socket-A connection

The Duron processor is a Celeron clone processor that conforms to

the AMD Socket-A specification The Duron features processor

speeds between 600MHz and 1.3 GHz It includes a 128KB L1 cache

and a 64KB L2 cache, and employs a 100MHz system bus Like the

newer Celerons, the Duron is constructed using 0.18 micron IC

man-ufacturing technology

Table 13.2 shows the relationship between the various numbering

systems In addition to the 8086 numbering system, Intel used a Px

identification up to the Pentium II The Pentium II is identified as the

Klamath processor Subsequent improved versions have been dubbed

Deschutes, Covington, Mendocino, Katmai, Willamette, Flagstaff

(P7), Merced, and Tahoe

F I G U R E 1 3 8

The Slot-A Athlon processor.

OverDrive processors The OverDrive unit may just be the same type

of microprocessor running at a higher clock speed, or it may be anadvanced architecture microprocessor designed to operate from thesame socket/pin configuration as the original To accommodate thisoption, Intel created specifications for eight socket designs, designat-

ed Socket-1 through Socket-8

The specifications for Socket-1 through Socket-3 were developed for80486SX, 80486DX, and 80486 OverDrive versions that use differ-ent pin numbers and power-supply requirements Likewise, Socket-4through Socket-6 specifications deal with various Pentium andOverDrive units that use different speeds and power-supply require-ments The Socket-7 design works with the fastest Pentium units and

includes provision for a voltage regulator module (VRM) to permit

various power settings to be implemented through the socket.The Socket-7 specification corresponds to the second generation ofPentium devices that employ SPGA packaging It is compatible withthe Socket-5, straight-row PGA specification that the first-generationPentium processors employed The Socket-8 specification is specific

to the Pentium Pro processor

The Socket-7 specification has been upgraded to include a new

stan-dard called Super Socket 7 This stanstan-dard extends the use of the

Socket-7 physical connector by adding a support signal required forimplementing AGP slots and the 100MHz front-side bus

specification Microprocessors designed to use the Super Socket 7

specification include AMD’s K6-2, K6-2+, and K6-III, along with

Intel’s Pentium MMX and Pentium Pro

Although the Intel Slot 1 design was originally developed for the

Pentium II, it also serves its Celeron and Pentium III processor

designs Like Socket 7, the Slot 1 specification provides for variable

processor core voltages (2.8 to 3.3) that permit faster operation and

reduced power consumption In addition, some suppliers have

creat-ed daughterboards containing the Pentium Pro processor that can be

plugged into the Slot 1 connector This combination Socket 8/Slot 1

device is referred to as a slotket processor.

The Slot 2 specification from Intel expands the Slot 1 SECC

technol-ogy to a 330-contact (SECC-2) cartridge used with the Intel Xeon

processor

AMD produced a reversed-version of the Slot 1 specification for its

Athlon processor by turning around the contacts of the Slot 1 design

It titled the new design Slot-A While serving the same ends as the

Slot 1 design, the Slot-A and Slot 1 microprocessor cartridges are not

compatible

In a departure from its proprietary Slot connector development, Intel

introduced a new ZIF socket standard, called Socket 370, for use

with its Celeron processor There are actually two versions of the

Socket 370 specification The first is the PPGA 370 variation

intend-ed for use with the Plastic Pin Grid Array (PPGA) version of the

Celeron CPUs The other is the Flip Chip Pin Grid Array (FC-PGA)

version

The term Flip Chip is used to describe a group of microprocessors

that have provisions for attaching a heat sink directly to the

micro-processor die The micro-processors in this category include the Cyrix III,

Celeron, and Pentium III Although the PPGA and FC-PGA

proces-sors both plug into the 370 socket, that does not mean they will work

in system board designs for the other specifications

Likewise, AMD produced a 462-pin ZIF socket specification for the

PGA versions of its Athlon and Duron processors No other

proces-sors have been designed for this specification, and only two chipsets

have been produced to support it

Table 13.3 summarizes the attributes of the various industry socket

and slot specifications

T A B L E 1 3 3

I N D U S T R Y S O C K E T / S L O T S P E C I F I C A T I O N S

C H A L L E N G E # 1

Your company does not want to replace all its computers at this time As a matter

of fact, what it really wants to do is spend a little money to upgrade all its ers as much as it can now and wait as long as possible to replace them Becauseyou are the Technical Services Manager, management has asked you for a plan

comput-to upgrade the systems You know that nearly all the systems in the company arePentium II 350MHz machines What is the most current, fastest upgrade you canrecommend to your board of directors?

Refer to the “Challenge Solutions” section at the end of this chapter for the lution to the challenge

Know which processors can be used with

Slot 1 and Socket 370 connections Also

know which processors can be used in

Slot-A

M ICROPROCESSOR C LOCK S PEEDS

In the Pentium processor, two speed settings are established for the

microprocessor: one speed for its internal core operations and a

sec-ond speed for its external bus transfers These two operational speeds

are tied together through an internal clock multiplier system The

Socket-7 specification enabled system boards to be configured for

different types of microprocessors using different operating speeds

In older systems, the operating speed of the microprocessor was

con-figured through external settings

Prior to Pentium II, all Pentium processors used 50, 60, or 66MHz

external clock frequencies to generate their internal operating

fre-quencies The value of the internal multiplier was controlled by

external hardware jumper settings on the system board

Pentium II processors moved to a 100MHz external clock and

front-side bus The Pentium III and all slot processors up to 1GHz

contin-ued to use the 100MHz clock and FSB However, beginning with the

Pentium III Coppermine, the external clock speed was increased to

133MHz At the same time, the Celeron processors retained the

66MHz clock and bus speeds up to the 800MHz Celeron versions

The Pentium 4 processors use external clocks of 100MHz and

133MHz From these clock inputs, the Pentium 4’s internal clock

multipliers generate a core frequency of up to 3.06GHz and

front-side bus frequencies of 400MHz, 533MHz, and 800MHz They have

also used four different special memory buses with different memory

types In Pentium 4 systems, it is possible to set clock speeds for the

memory and front-side buses independently The different memory

bus configurations are designed to work with different types of

RDRAM and run at speeds of 400MHz, 600MHz, and 800MHz

Beginning with the Pentium MMX, Intel adopted dual-voltage

sup-ply levels for the overall IC and for its core Common Intel voltage

supplies are +5/+5 for older units and +3.3/+3.3, +3.3/+2.8,

+3.3/+1.8, and +3.3/1.45 for newer units

Clone processors may use compatible voltages (especially if they arepin compatible) or may use completely different voltage levels.Common voltages for clone microprocessors include +5, +3.3, +2.5,and +2.2 The additional voltage levels are typically generatedthrough special regulator circuits on the system board In each case,you should consult the system board’s user guide anytime youreplace or upgrade the microprocessor.

From the Socket 7 processors until now, systems use a voltage lator module (VRM) to supply special voltage levels for differenttypes of microprocessors that might be installed The module may bedesigned as a plug-in module so that it can be replaced easily in case

regu-of component failure This is a somewhat common occurrence withvoltage regulator devices It also enables the system board to beupgraded when a new Pentium device that requires a different volt-age level or a different voltage pairing is developed

Some multiprocessor system boards have spaces for two or moreVRMs to be installed The additional modules must be installed inVRM sockets, as illustrated in Figure 13.9, to support additionalprocessors VRMs can also be a source of server board failures Youshould always check the processor voltages on a malfunctioning sys-tem board to verify that they are being supplied correctly

The Pentium processor requires the presence of a heat-sinking device and a microprocessor fan unit for cooling purposes As Figure 13.10 illustrates, these devices come in many forms, including simple pas-

sive heat sinks and fan-cooled, active heat sinks.

Passive heat sinks are finned metal slabs that can be clipped or gluedwith a heat-transmitting adhesive onto the top of the microprocessor.The fins increase the surface area of the heat sink, enabling it to dis-sipate heat more rapidly Active heat sinks add a fan unit to move airacross the heat sink The fan moves the heat away from the heat sinkand the microprocessor more rapidly

ATX-style systems employ power supplies that use a reverse-flow fanthat brings in cool air from the back of the unit and blows it directly onthe microprocessor For this system to work properly, the system board

must adhere to the ATX form factor guidelines and place the

micro-processor in the correct position on the system board In theory, this

design eliminates the need for special microprocessor cooling fans

In newer Pentium systems, the BIOS interrogates the processor ing startup and configures it appropriately This prevents the userfrom subjecting the processor to potentially destructive conditions,such as overclocking In addition, these systems can monitor the

dur-health of the processor while it is in operation and take steps to

com-pensate for problems such as overheating Such steps normallyinvolve speeding up or slowing down the processor fan to maintain agiven operating temperature

Most Pentium system boards are designed to support a number ofdifferent microprocessor types and operating speeds In olderPentium systems, the microprocessor’s configuration settings wereestablished largely through jumpers on the system board These set-tings typically included such items as

➤ Microprocessor Type—This setting tells the system what type

of processor is installed If this setting is incorrect, the systemassumes that the installed processor is the one specified by thesetting and tries to interact with it on that basis Depending onwhich microprocessor is indicated, the system POST may iden-tify the processor incorrectly and still run, but not properly Inother cases, the processor may lock up during the POST or notrun at all In either case, the processor could be damaged

➤ Core-to-Bus Speed Ratio—Again, depending on the exact

mis-match, the system may overclock the processor and run, buterratically If the overclocking is less than 20%, the systemmay run without problems; however, the processor’s lifeexpectancy is decreased If the deviation is greater than 20%,the system may not come up at all, and the processor may bedamaged

➤ Bus Frequency Setting—Configuring this setting incorrectly

causes the processor to run faster or slower Users commonlyemploy this method to increase the operating speed of theirolder systems If the variation is less than 20%, the system willprobably work with a shortened processor life Greater levels

of overclocking the bus may cause the system to have randomlockups