PC Diagnostics, Testing, and Maintenance

PC Diagnostics

No matter how well built your PC is and how well written its software, something is eventually going to

go wrong, and you might not always have a support system available to resolve the problem. Diagnostic

software can be vitally important to you anytime your computer malfunctions or you are in the process

of upgrading a system component or especially building an entirely new system from scratch. This chapter

examines the types of diagnostics software available, and particularly those utilities you might already

own because they are included with common operating systems and hardware products.

You also might find that your system problems are caused by a hardware malfunction and that you must

open the computer case to perform repairs. This chapter also examines the tools and testers used to upgrade

and repair PCs—both the basic items every user should own and some of the more advanced devices.

Of course, the best way to deal with a problem is to prevent it from occurring in the first place. The preventive

maintenance sections of this chapter describe the procedures you should perform on a regular basis

to keep your system in good working order. This chapter describes several levels of diagnostic software that

are either included with your system or available from your system manufacturer and third parties. This

chapter describes how you can get the most from this software. It also details the various ROM BIOS audio

codes and error codes and examines aftermarket diagnostics and public-domain diagnostic software.

Diagnostics Software

Several types of diagnostic software are available for PCs. Some diagnostic functions are integrated into

the PC hardware or into peripheral devices, such as expansion cards, whereas others take the form of

operating system utilities or separate software products. This software, some of which is included with the

system when purchased, assists users in identifying many problems that can occur with a computer’s

components. In many cases, these programs can do most of the work in determining which PC component

is defective or malfunctioning. The types of diagnostic software are as follows:

■ POST. The power on self test operates whenever any PC is powered up (switched on). These routines

are contained within the motherboard ROM as well as ROMs on expansion cards.

■ Manufacturer-supplied diagnostics software. Many of the larger manufacturers—especially high-end,

name-brand manufacturers such as IBM, Hewlett-Packard, Dell, and others—make special diagnostics

software expressly designed for their systems. This manufacturer-specific software normally consists

of a suite of tests that thoroughly examines the system. In some cases, these utilities are

included with the system, or you can download these diagnostics from the manufacturer’s online

services at no charge; otherwise, you might have to purchase them. Many vendors include a limited

version of one of the aftermarket packages that has been customized for use with their systems. In

some older IBM and Compaq systems, the diagnostic software is installed on a special partition on

the hard drive and can be accessed during startup. This was a convenient way for those system

manufacturers to ensure that users always had diagnostics available.

■ Peripheral diagnostics software. Many hardware devices ship with specialized diagnostics software

designed to test their particular functions. Adaptec SCSI host adapters, for example, include diagnostic

functions in the card’s ROM BIOS that you can access with a keystroke (Ctrl+A) at boot

time. Sound cards normally include a diagnostic program on a disk along with the drivers, which

test and verify all the card’s functions. Network adapters usually include a diagnostic specific to

that adapter on a disk, also normally with the drivers. Other devices or adapters also might provide

a diagnostic program or disk, usually included with the drivers for the device.

■ Operating system diagnostics software. Operating systems, such as Windows 9x/Me and Windows

NT/2000/XP, include a variety of diagnostic software utilities designed to identify and monitor

the performance of various components in the computer.

■ Aftermarket diagnostics software. A number of manufacturers make general-purpose diagnostics

software for PCs. This type of software is often bundled with other system maintenance and

repair utilities to form a general PC software toolkit.

The Power On Self Test

When IBM first began shipping the original PC in 1981, it included safety features that had never been

seen in a personal computer. These features were the power on self test (POST) and parity-checked memory.

Although parity-checked or even error correcting code (ECC) memory is no longer available in most

low-end chipsets, every PC still executes a POST when you turn it on. The following sections provide more

detail on the POST, a series of program routines buried in the motherboard ROM-BIOS chip that tests all

the main system components at power-on time. This series of routines is partially responsible for the delay

when you turn on your PC; the computer executes the POST before loading the operating system.

What Is Tested?

Whenever you start up your computer, it automatically performs a series of tests that checks the primary

components in your system, such as the CPU, ROM, motherboard support circuitry, memory,

and major peripherals such as the expansion chassis. These tests are brief and are designed to catch

hard (not intermittent) errors. The POST procedures are not very thorough compared with available

disk-based diagnostics. The POST process provides error or warning messages whenever it encounters a

faulty component.

Although the diagnostics performed by the system POST are not very thorough, they are the first line

of defense, especially when it comes to detecting severe motherboard problems. If the POST encounters

a problem severe enough to keep the system from operating properly, it halts the system boot

process and generates an error message that often identifies the cause of the problem. These POSTdetected

problems are sometimes called fatal errors because they prevent the system from booting.

How Errors Are Displayed

The POST tests normally provide three types of output messages: audio codes, onscreen text messages,

and hexadecimal numeric codes that are sent to an I/O port address.

POST errors can be displayed in the following three ways:

■ Beep codes. Heard through the speaker attached to the motherboard.

■ POST checkpoint codes. Hexadecimal checkpoint codes sent to an I/O port address. A special card

plugged into either an ISA or a PCI card slot is required to view these codes.

■ Onscreen messages. Error messages displayed onscreen after the video adapter is initialized.

BIOS POST Beep Codes

Beep codes are used for fatal errors only, which are errors that occur so early in the process that the

video card and other devices are not yet functional. Because no display is available, these codes take

the form of a series of beeps that identify the faulty component. When your computer is functioning

normally, you should hear one short beep when the system starts up at the completion of the POST,

although some systems (such as Compaq’s) beep twice at the end of a normal POST. If a problem is

detected, a different number of beeps sounds, sometimes in a combination of short and long tones.

BIOS POST Checkpoint Codes

POST checkpoint codes are hexadecimal numeric codes written by POST routines to I/O port address

80h as each major step is begun. These are often simply called POST codes. These POST codes can be

read by only a special adapter card plugged into one of the system slots. These cards originally were

designed for system manufacturers to use for burn-in testing of the motherboard. Several companies

make these cards available to technicians. Micro 2000, JDR Microdevices, Data Depot, Ultra-X, and

Trinitech are just a few manufacturers that market these POST cards. See the vendor list on the accompanying

disc for more information about these manufacturers.

POST checkpoint codes can be used to track the system’s progress through the boot process from poweron

right up to the point at which the bootstrap loader runs (when the operating system load begins).

When you plug a POST code reader card into a slot, during the POST you will see two-digit hexadecimal

numbers flash on the card’s display. If the system stops unexpectedly or hangs, you can identify the test

that was in progress during the hang from the two-digit code. This step usually helps to identify the

malfunctioning component.

Most older POST reader cards plug into the 8-bit connector that is a part of the ISA or EISA bus. Many

systems—even those with PCI slots—still have ISA connectors. In that case, those cards are adequate.

However, the motherboards found in most newer PCs have no ISA slots at all, so obviously an ISA POST card

won’t work. Virtually all the companies that make POST cards also make PCI versions. Micro 2000 has a

card called the Post-Probe, which has both ISA and PCI connectors on the same board. PC Certify has a similar card called the PCISA FlipPOST (see Figure 24.1). Both companies also have separate Micro Channel

Architecture (MCA) bus adapters that allow POST cards to work in older IBM PS/2 systems with the MCA bus.

No matter what, be sure your POST card works in a PCI slot if you are working on modern PCs. Most

newer systems don’t have ISA slots, and you will rarely encounter any MicroChannel slots. If you

maintain older Compaq or EISA-based systems from any vendor, these systems might use an I/O port

address other than port 80. Simpler POST cards monitor only port 80, but more sophisticated cards have DIP switches or jumper blocks to configure the card to monitor the different I/O port addresses used by Compaq and EISA-based systems.

BIOS POST Onscreen Messages

Onscreen messages are brief messages that attempt to indicate a specific failure. These messages can be

displayed only after the point at which the video adapter card and display have been initialized.

These different types of error messages are BIOS dependent and vary among BIOS manufacturers, and even

in some cases among different BIOSs from the same manufacturer. The following sections list the codes

used by the most popular ROM BIOS versions (AMI, Award, Phoenix, and IBM BIOS), but you should consult

your motherboard or ROM BIOS manufacturer for the codes specific to your board and BIOS.

AMI BIOS POST Beep Codes

Award BIOS and Phoenix FirstBIOS POST Error Codes

Currently, only one standard beep code exists in the Award BIOS (also known as the Phoenix FirstBIOS).

A single long beep followed by two short beeps indicates that a video error has occurred and that the

BIOS cannot initialize the video screen to display any additional information. If multiple or continuous

beeps occur with an Award BIOS, this usually indicates problems with the power supply or memory.

Phoenix BIOS 5.x and Earlier POST Beep Codes

Phoenix BIOS 6.x and Later POST Beep Codes

IBM BIOS Beep Codes

IBM BIOS POST/Diagnostics Display Error Codes

Operating System Diagnostics

In many cases, it might not be necessary to purchase third-party diagnostic software because your operating

system has all the diagnostic tools you need. Windows 9x/Me and NT/2000/XP include a large

selection of programs that enable you to view, monitor, and troubleshoot the hardware in your system.

Windows XP has numerous tools, utilities, and error-reporting features that can be useful in helping

you determine the cause of problems. The most serious problems can be caused by corrupt files or

buggy software on the system, as well as defective or incorrectly configured hardware, and will often

result in a STOP or “blue-screen” error, causing Windows to enter a special debugging mode. When

this happens, Windows XP is normally configured to save a dump of the error in a memory dump

file, which can be useful if it is a software bug you are going to report to Microsoft. Still, it is always a

good idea to write down the error for future reference.