THE PROCESS OF FAULT DIAGNOSIS
The
Universal Troubleshooting Process
Regardless of how
complex your particular computer or
peripheral device might be, a dependable troubleshooting procedure can be
broken down into four basic steps (Fig. 4-1): define your symptoms, identify
and isolate the potential source (or location) of your problem, replace the
suspected sub-assembly, and re-test the unit thoroughly to be sure that you
have solved the problem. If you have not solved the problem, start again from
Step #1
This is a “universal”
procedure that you can apply to any sort of troubleshooting—not just for
personal computer equipment.
Define
Your Symptoms
When a PC breaks down,
the cause might be as simple as a loose wire or connector, or ascomplicated as
an IC or sub-assembly failure. Before you open your tool box, you must have a
firm understanding of all the symptoms. Think about the symptoms carefully—for
example:
- Is the disk or tape inserted properly?
- Is the power or activity LED lit?
- Does this problem occur only when the
computer is tapped or moved?
By recognizing and
understanding your symptoms, it can be much easier to trace a problem to the
appropriate assembly or component. Take the time to write down as many symptoms
as you can. This note-taking might seem tedious now, but once you have begun
your repair, a written record of symptoms and circumstances will help to keep
you focused on the task at hand. It will also help to jog your memory if you
must explain the symptoms to someone
else at a later date.
As a professional troubleshooter, you must of-ten log problems or otherwise
document your activities anyway.
Identify
and Isolate
Before you try to
isolate a problem within a piece of computer hardware, you must first be sure
that the equipment itself is causing the problem. In many circumstances, this
will be fairly obvious, but some situations might appear ambiguous (i.e., there
is no power, no DOS prompt, etc.). Always remember that a PC works because of
an intimate mingling of hardware and software. A faulty or improperly
configured piece of software can cause confusing system errors. Chapter 3
touched on some of the problems that operating systems can encounter.
When you are confident
that the failure lies in your system’s hardware, you can begin to identify
possible problem areas. Because this book is designed to deal with sub-assembly
troubleshooting, start your diagnostics there. The troubleshooting procedures throughout this
book will guide you through the major sections of today’s popular PC components
and peripherals, and aid you in deciding which sub-assembly might be at fault.
When you have identified a potential problem area, you can begin the actual repair process and swap the
suspect sub-assembly.
Replace
Because computers and
their peripherals are designed as collections of sub-assemblies, it is almost
always easier to replace a sub-assembly outright, rather than attempt to
troubleshoot the sub-assembly to its component level. Even if you had the time,
documentation, and test equipment to isolate a defective component, many
complex parts are proprietary, so it is highly unlikely that you would be able
to obtain replacement components without a significant hassle. The labor and
frustration factor involved in such an endeavor is oftenjust as expensive as
replacing the entire sub-assembly to begin with (perhaps even moreexpensive).
On the other hand, manufacturers and their distributors often stock a selection
of sub-assemblies and supplies. You might need to know the manufacturers part
number for the sub-assembly to obtain a new one.
During a repair, you
might reach a roadblock that requires you to leave your equipment fora day or
two, or maybe longer. This generally happens after an order has been placed for
new parts, and you are waiting for those parts to come in. Make it a point to reassemble
your system as much as possible before leaving it. Gather any loose parts in
plastic bags, seal them shut, and mark them clearly. If you are working with
electronic circuitry, be sure to use good-quality anti-static boxes or bags for
storage. Partial re-assembly (combined
with careful notes)
will help you remember how the unit goes together later on. Another problem
with the fast technological progress we enjoy is that parts rarely stay on the
shelf long. That video board you bought last year is no longer available.
Changing
Parts
Once a problem is
isolated, technicians face another problem: the availability of spare parts.
Novice technicians often ask what kinds and quantity of spare parts they should
keep on hand. The best answer to give here is simply: none at all. The reason for
this somewhat drastic answer is best explained by the two realities of PC
service.
Parts
Are Always Changing
After only 15 years or
so, the PC is in its sixth CPU generation (with such devices as the AMD K6 and
Intel Pentium II). As a result, a new generation matures every 24 to 36 months
(although the newer generations have been arriving in 18 to 24 months). Even
the “standardized” products, such as CD-ROM drives, have proliferated in
different speeds and versions (8, 10´, 12´, 16´, and even 20´ speeds). Once
production stops for a drive or board, stock rarely remains for very long. You
see, even if you know what the problem is, the chances of your locating an
exact replacement part are often quite slim if the part is more than two years
old. Notice the word exact—this is the key word in PC repair.
The Booting Process
Computer initialization
is a process—not en event. From the moment that power is applied until the
system sits idle at the command-line prompt or graphical desktop, the PC boot
process is a sequence of predictable steps that verify the system and prepare
it for operation.
By understanding each
step in system initialization, you can develop a real appreciation for the way
that hardware and software relate to one another—you also stand a much better
chance of identifying and resolving problems when a system fails to boot
properly. This part of the chapter provides a step-by-step review of a typical
PC boot process.
The
Boot Process 65G STARTED
The system to
initialize and run with flaws in the motherboard, memory, or drive systems can
have catastrophic consequences for files in memory or on disk. To ensure system
integrity, a set of hardware-specific self-test routines checks the major
motherboard components, and identifies the presence of any other specialized
BIOS ICs in the system (i.e., drive-controller BIOS, video BIOS, SCSI BIOS, and
so on). BIOS starts with a test of the motherboard hardware such as the CPU,
math co-processor, timer ICs, Direct Memory Access (DMA) controllers, and
interrupt (IRQ) controllers. If an error is detected in this early phase of
testing, a series of beeps (or beep codes) are produced. By knowing the BIOS
manufacturer and the beep code, you can determine the nature of the problem.
Chapter 15 deals with beep and error codes in more detail. Beep codes are used
because the video system has not been initialized.
Next, BIOS looks for
the presence of a video ROM between memory locations C000:0000h through
C780:000h. In just about all systems, the search will reveal a video BIOS ROM
on a video adapter board, plugged into an available expansion slot. If a video
BIOS is found, its contents are evaluated with a checksum test. If the test is
successful, control is transferred to the video BIOS, which loads and
initializes the video adapter.
When initialization is
complete, you will see a cursor on the screen and control returns to the system
BIOS. If no external video adapter BIOS
is located, the system BIOS will provide an initialization routine for
the motherboard’s video adapter and a cursor will also appear.
Once the video system
initializes, you are likely to see a bit of text on the display identifying the
system or video BIOS ROM maker and revision level. If the checksum test fails,
you will see an error message such as: C000 ROM Error or Video ROM Error.
Initialization will
usually halt right there. Now that the video system is ready, system BIOS will
scan memory from C800:0000h through DF80:0000h in 2KB increments to search for
any other ROMs that might be on other adapter cards in the system. If other
ROMs are found, their contents are tested and run. As each supplemental ROM is
executed, they will show manufacturer and revision ID information. In some
cases, a supplemental (or “adapter”) ROM might alter an existing BIOS ROM
routine. For example, an Ultra DMA/33 drive-controller board with its own
on-board ROM will replace the motherboard’s older drive routines. When a ROM
fails the checksum test, you will see an error message such as: “XXXX ROM
Error.” The XXXX indicates the segment
address where the faulty ROM was detected. If a faulty ROM is detected, system
initialization will usually halt.
Applying
Power
PC initialization
starts when you turn the system on. If all output voltages from the power
supply are valid, the supply generates a Power Good (PG) logic signal. It can
take between 100 ms and 500 ms for the supply to generate a PG signal. When the
motherboard timer IC receives the PG signal, the timer stops forcing a Reset
signal to the CPU. At this point, the CPU starts processing.
The
Bootstrap
The very first
operation performed by a CPU is to fetch an instruction from address
FFFF:0000h. Because this address is almost at the end of available ROM space,
the instruction is almost always a jump command (JMP) followed by the actual
BIOS ROM starting address. By making all CPUs start at the same point, the BIOS
ROM can then send program control anywhere in the particular ROM (and each ROM
is usually different).
This initial search of
address FFFF:0000h and the subsequent re-direction of the CPU is traditionally
referred to as the bootstrap in which the PC “pulls itself up by its
bootstraps”—or gets itself going. Today, we have shortened the term to boot,
and have broadened its meaning to include the entire initialization
process.
Core
Tests
The core tests are part
of the overall Power-On Self-Test (POST) sequence, which is the most important
use of a system BIOS during initialization. As you might expect, allowing on
the display (and system initialization will halt). Remember that POST codes and
theirmeanings will vary slightly between BIOS manufacturers. If the POST
completes successfully, the system will respond with a single beep from the
speaker. Chapter 15 covers I/O port POST codes.
Finding
the OS
The system now needs to
load an operating system (usually DOS or Windows 95). The first step here is to
have the BIOS search for a DOS volume boot sector (VBS) on the A: drive. If
there is no disk in the drive, you will see the drive light illuminate briefly,
and then BIOS will search the next drive in the boot order (usually drive C:).
If a disk is in drive A:, BIOS will load sector 1 (head 0, cylinder 0) from the
disk’s DOS volume boot sector intomemory, starting at 0000:7C00h. There are a
number of potential problems when
attempting to load the VBS. Otherwise, the first program in the directory
(IO.SYS) will begin to load, followed by MSDOS.SYS.
- If the first byte of the DOS VBS is less than
06h (or if the first byte is greater than or equal to 06h and next nine words
of the sector contain the same data pattern), you will see an error message
similar to: “Diskette boot record error.”
- If the IO.SYS and MSDOS.SYS are not the first
two files in the directory (or some other problem is encountered in loading),
you’ll see an error such as: “Non-system disk or disk error.”
- If the boot sector on the diskette is
corrupted and cannot be read (DOS 3.3 or earlier), you’ll probably get a Disk
boot failure message.
If the OS cannot be
loaded from any floppy drive, the system will search the first fixed drive
(hard drive). Hard drives are a bit more involved than floppy disks.
BIOS loads sector 1
(head 0, cylinder 0) from the hard drive’s master partition boot sector (called
the master boot sector, MBS) into memory, starting at 0000:7C00h, and the last
two bytes of the sector are checked. If the final two bytes of the
master-partition boot sector are not 55h and AAh respectively, the boot sector
is invalid, and you will see an error message similar to: “No boot device
available and system initialization will halt.” Other systems might depict the
error differently or attempt to load ROM BASIC. If the BIOS attempts to load
ROM BASIC and there is no such feature in the BIOS, you’ll see a ROM BASIC
error message.
Otherwise, the disk
will search for and identify any extended partitions (up to 24 total
partitions). Once any extended partitions have been identified, the drive’s
original boot sector will search for a boot-indicator byte, marking a partition
as active and bootable. If none of the partitions are marked as bootable (or if
more than one partition is marked bootable), a disk error message will be
displayed such as: “Invalid partition table.” Some older BIOS versions might
attempt to load ROM BASIC, but will generate an error message in most cases
anyway.
When an active bootable
partition is found in the master partition boot sector, the DOS Volume Boot
Sector (VBS) from the bootable partition is loaded into memory and tested. If
the DOS VBS cannot be read, you will see an error message similar to: “Error loading
operating system.” When the DOS volume boot sector does load, the last two
bytes are
Loading
the OS
If no problems are
detected in the disk’s DOS volume boot sector, IO.SYS (or IBM-BIO. COM) is
loaded and executed. If Windows 95 is on the system, IO.SYS might be re-named
WINBOOT.SYS, which will be executed instead. IO.SYS contains extensions to BIOS
that start low-level device drivers for such things as the keyboard, printer,
and block devices. Remember that IO.SYS also contains initialization code that
is only needed during system startup. A copy of this initialization code is
placed at the top of conventional memory which takes over initialization. The
next step is to load MSDOS.SYS (or IBM-DOS. COM), which is loaded so that it
overlaps the part of IO.SYS containing the initialization code. MSDOS.SYS (the
MS-DOS kernel) is then executed to initialize base device drivers, detect
system status, reset the disk system, initialize devices (such as the printer
and serial port), and set up system-default parameters. The MS-DOS essentials
are now loaded and control returns to the IO.SYS/WINBOOT.SYS initialization
code in memory.
Establishing
the Environment
If a CONFIG.SYS file is
present, it is opened and read by IO.SYS/WINBOOT.SYS. The DEVICE statements are
processed first in the order they appear, then INSTALL statements are processed
in the order they appear. A SHELL statement is handled next. If no SHELL
statement is present, the COMMAND.COM processor is loaded. When COMMAND. COM is loaded, it overwrites
the initialization code left over from IO.SYS (which is now no longer needed).
Under Windows 95, COMMAND.COM is loaded only if an AUTOEXEC.BAT file is present
to rocess the AUTOEXEC.BAT statements. Finally, all other statements in
CONFIG.SYS are processed, and WINBOOT.SYS also looks for the SYSTEM.DAT
registry file. When an UTOEXEC.BAT file is present, COMMAND.COM (which now has
control of the system) will load and execute the batch file. After the
batch-file processing is complete, the
familiar DOS prompt will appear. If there is no AUTOEXEC.BAT in the root
directory, COMMAND.COM will request the current date and time, then show the
DOS For Windows 95 systems, IO.SYS (or WINBOOT.SYS) combines the functions of
IO.SYS and MSDOS.SYS.
Creating
a DOS Boot Disk
The most persistent
problem with PC troubleshooting is that it can be difficult to boot a system
successfully—especially if there are hard-drive problems. This makes it
particularly important to have a bootable floppy diskette on hand. The two means
of creating a boot disk are: utomatically (through an existing Windows 95
platform) or manually (through a DOS6.22 platform). In either case, you’re
going to need access to a running PC with an operating system that is similar
to the version you plan to install on the new PC. Windows 95 Windows 95 comes
with an automatic “Startup Disk” maker. If you have access to a Windows 95
system, use the following procedure to create a DOS 7.x startup disk: Label a
blank diskette and insert it into your floppy drive.- Click on Start, Settings,
and Control Panel. - Double-click on the
Add/remove programs icon.
- Select the Startup disk tab.
- Click on Create disk.
- The utility will
remind you to insert a diskette, then prepare the disk automatically.
When the preparation is
complete, test the diskette. The preparation process takes several minutes, and
will copy the following files to your
diskette: ATTRIB, CHKDSK, COMMAND, DEBUG, DRVSPACE.BIN, EDIT, FDISK,
FORMAT, REGEDIT, SCANDISK, SYS, and
UNINSTAL. All of these files are DOS 7.x-based files, so you can run them from
the A: prompt.
The Windows 95 FDISK
utility has been reported to have a bug that can cause problems when creating
more than one partition on the same drive. Later releases of Windows 95 (i.e.,
OSR 2) claim to have corrected this issue, but if you encounter problems with
FDISK, use the DOS 6.22 version. Process of Fault Diagnosis
Before getting into the
troubleshooting details, it is important to know about what goes on during the
startup process. The reason is, there are actually quite a few steps that occur
in between switching the power ON and hearing the familiar Windows 95, 98 or
Windows ME./XP startup sounds and seeing the Windows desktop. In fact, there are
a whole series of files that are automatically loaded one after the other when
you turn your computer on. The trick with troubleshooting startup problems is
trying to figure out which of those files (or what step in the process) causes
a specific problem in the computer. If we know approximately where in the
startup process the problem occurs (Computer gets stuck), we can diagnose the
problem easily.
This explains the
various problems that occur in a computer and the troubleshooting procedures.
The system to initialize and run with flaws in the motherboard, memory, or
drive systems can have catastrophic consequences for files in memory or on
disk. To ensure system integrity, a set of hardware-specific self-test routines
checks the major motherboard components, and identifies the presence of any
other specialized BIOS ICs in the system (i.e., drive-controller BIOS, video
BIOS, SCSI BIOS, and so on). BIOS zstarts with a test of the motherboard
hardware such as the CPU, math co-processor, timer ICs, Direct Memory Access
(DMA) controllers, and interrupt (IRQ) controllers.
If an error is detected
in this early phase of testing, a series of beeps (or beep codes) are produced.
By knowing the BIOS manufacturer and the beep code, you can determine the
nature of the problem. Chapter 15 deals with beep and error codes in more
detail. Beep codes are used because the video system has not been initialized.
Next, BIOS looks for the presence of a video ROM between memory locations
C000:0000h through C780:000h. In just about all systems, the search will reveal
a video BIOS ROM on a video adapter board, plugged into an available expansion
slot. If a video BIOS is found, its contents are evaluated with a checksum
test. If the test is successful, control is transferred to the video BIOS,
which loads and initializes the video adapter.
When initialization is
complete, you will see a cursor on the screen and control returns to the system
BIOS. If no external video adapter BIOS
is located, the system BIOS will provide an initialization routine for
the motherboard’s video adapter and a cursor will also appear.
Once the video system
initializes, you are likely to see a bit of text on the display identifying the
system or video BIOS ROM maker and revision level. If the checksum test fails,
you will see an error message such as: C000
ROM Error or Video ROM Error.
Initialization
will usually halt right there.
Now that the video
system is ready, system BIOS will scan memory from C800:0000h through
DF80:0000h in 2KB increments to search for
any other ROMs that might be on other adapter cards in the system. If
other ROMs are found, their contents are tested and run. As each supplemental
ROM is executed, they will show manufacturer and revision ID information. In
some cases, a supplemental (or “adapter”) ROM might alter an existing BIOS ROM
routine. For example, an Ultra DMA/33 drive-controller board with its own
on-board ROM will replace the motherboard’s older drive routines. When a ROM
fails the checksum test, you will see an error message such as: “XXXX ROM
Error.” The XXXX indicates the segment address where the faulty ROM was
detected. If a faulty ROM is detected, system initialization will usually halt.
Post
BIOS then checks the
memory location at 0000:0472h. This address contains a flag that
determines whether the
initialization is a cold start (power first applied) or a warm start (re-set
button or ++ key combination). A value of
1234h at this address indicates a warm start—in which case, the (POST) routine
is skipped. If any other value is found at that location, a cold start is
assumed, and the full POST routine will be executed. The full POST checks many
of the other higher-level functions on the motherboard, memory, keyboard, video
adapter, floppy drive, math co-processor, printer port, serial port, hard
drive, and other sub-systems. Dozens of tests are performed by the POST.
When an error is
encountered, the single-byte POST code is written to I/O port 80h, where it
might be read by a POST-code reader. In other cases, you might see an error
message
BIOS
When your computer is
first turned on, it automatically loads a program called the BIOS, or Basic
Input/Output System, which is stored on a special chip on your computer’s
motherboard. The BIOS is essentially a combination of software and hardware in that it consists
of software, but the contents of that software is stored in a hardware chip. One of the first things we should see on your
computer’s monitor when we start the PC is some type of message like "Hit
Esc to enter Setup," although instead of Esc it may say F2 or F10 or any
number of other keys and instead of Setup it may say CMOS Setup or BIOS Setup
or just CMOS. Make note of the key required to enter the Setup program because
we may need that later (some startup problems can only be solved by changing
some BIOS/CMOS settings via the Setup program).
Power-On
Self Test (POST)
The first thing that
the BIOS does when it boots the PC is to perform what is called the Power-On
Self-Test, or POST for short. The POST is a built-in diagnostic program that
checks the hardware to ensure that everything is present and functioning
properly, before the BIOS begins the actual boot. It later continues with additional
tests such as the memory test and then it lists any devices that it finds
attached to the computer’s internal IDE controller(s). (that is seen on the
screen of the monitor) as the boot process is proceeding. The POST runs very
quickly, and you will normally not even noticed that it is happening--unless it
finds a problem. You may have encountered a PC that, when turned on, made
beeping sounds and then stopped without booting up. That is the POST telling
you something is wrong with the machine. The speaker is used because this test
happens so early on, before the video is activated! These beep patterns can be
used to diagnose many hardware problems with the PC. The exact patterns depend
on the maker of the BIOS; the most common are Award and AMI BIOS.
BIOS
Startup Screen
When the system BIOS
starts up, you will see its familiar screen display, normally after the video
adapter displays its information. These are the contents of a typical BIOS
start up screen:
• The BIOS Manufacturer and Version
Number.
• The BIOS Date: The date of the BIOS can be
important in helping you determine its capabilities.
• Setup Program Key: The key or keys to press
to enter the BIOS setup program. (This is usually {Del}, sometimes {F2}, and
sometimes another key combination.
• System Logo: The logo of the BIOS company, or
in some cases the PC maker or motherboard manufacturer.
• The "Energy Star" Logo: This
distinctive logo is displayed if the BIOS supports the Energy Star standard,
which almost all newer ones do.
• The BIOS Serial Number: This is normally
located at the bottom of the screen. Since BIOSes are highly customized to the
particular motherboard, this serial number can be used in many cases to
determine the specific motherboard and BIOS version you are using. Check out
WimBervoets' BIOS site for a huge list of these numbers
Troubleshooting
BIOS Beep Codes
When a problem is
identified with the system during the POST, the BIOS will normally produce an
error message. However, in some cases the problem is detected so early in the
test that the BIOS cannot even access the video card to print the message! In
this case the BIOS will produce a beeping pattern on the speaker to tell you
what the problem is. The exact meaning
of the beep codes depends on the type
and version of BIOS that you have. The three most popular types of BIOS are
those made by Award, American Megatrends (AMI) and Phoenix. The beep codes for
these BIOS products are described in this part of the troubleshooter. If you
are using a PC made by a company that writes its own BIOS, you will have to
consult your owner's manual A single beep during the boot process, usually
right before the BIOS startup screen is displayed, is normal and does not
indicate a failure as long as the boot continues on.
Beep codes can be in
several different patterns, depending on the BIOS that you are using. Some
BIOSes use very simple beep codes in a pattern of varying numbers of short
beeps, while others may mix short and long beeps. The Phoenix BIOS is famous
for its complicated beep patterns that are actually in up to four groups--one
or more beeps and then a pause, followed by as many as three more
patterns.
Fault
Report Forms
To make maintenance easy forms are needed to document
systems and corresponding fault 1. PC configuration form Use this form when
installing or configuring the PC and its expansion boards. 2. System CMOS sheet
Use this form to record system parameters (as shown in the system SETUP
screens).
3. BIOS upgrade Use
this form when planning a BIOS upgrade for your PC.
4. Customer billing a
simple time and material form for beginning technicians. Usage of Software
Diagnostic Programs for Hardware
Diagnostic
Programs
Software and hardware
complement one another Diagnostic program is used to detect both hardware and
software problems the computer memory can be diagnosed to known the size the
processor types too can also be checked to do these well one has to know how to
distinguish hardware problem from the software.
Bench
Marking
We all know that
today’s personal computers are capable of astounding performance. If you doubt
that, consider any of the current 3D games, such as Quake II or Monster Truck
Madness. However, it is often important to quantify the performance of a
system. Just saying that a PC is “faster” than another system is simply not
enough—we must often apply a number to that performance to measure the
improvements offered by an upgrade, or to objectively compare the performance
of various systems. Benchmarks are used to test and report the performance of a
PC by running a set of well-defined tasks on the system. A benchmark program
has several different uses in the PC industry depending on what you’re needs
are:
System Comparisons:
Benchmarks are often used to compare a system to one or more competing machines
(or to compare a newer system to older machines). Just flip through any issue
of PC Magazine or Byte, and you’ll see a flurry of PC ads all quoting numerical
performance numbers backed up by benchmarks. You might also run a benchmark to
establish the overall performance of a new system before making a purchase
decision.
Upgrade Improvements:
Benchmarks are frequently used to gauge the value of an up-grade. By running
the benchmark before and after the upgrade process, you can get a numerical
assessment of just how much that new CPU, RAM, drive, or motherboard might have
improved (or hindered) system performance.
- Diagnostics Benchmarks sometimes have role in
system diagnostics. Systems that are performing poorly can be benchmarked as
key components are checked or reconfigured. This helps the technician isolate
and correct performance problems far more reliably than simple “visual”
observations.
Avoiding Benchmark
Problems One of the most serious problems encountered with benchmarks is the
integrity of their numbers. You’ve probably heard that “statistics can lie,”
and the same thing is true of benchmarks. In order for benchmarks to provide
you with reliable results, you must take some precautions:
- Note the complete system configuration When
you run a benchmark and achieve a result, be sure to note the entire system
configuration (i.e., CPU, RAM, cache, OS version, etc.).
- Run the same benchmark on every system
Benchmarks are still software, and the way in which benchmark code is written
can impact the way it produces results on a given computer. Often, two
different versions of the same benchmark will yield two different results. When
you use benchmarks for comparisons between systems, be sure to use the same
program and version number.
- Minimize hardware differences between
hardware platforms A computer is an assembly of many interdependent
sub-assemblies (i.e., motherboard, drive controllers, drives, CPU, etc.), but
when a benchmark is run to compare a difference between systems, that
difference can be masked by other elements in the system. For example, suppose
you’re using a benchmark to test the hard-drive data transfer on two systems.
Different hard drives and drive controllers will yield different results
(that’s expected). However, even if you’re
using identical drives and controllers, other differences between the
systems (such as BIOS versions, TSRs, OS
differences, or motherboard chipsets) can also influence different results.
- Run the benchmarks
under the same load The results generated by a benchmark do not guarantee that
same level of performance under “real-world” applications. This was one of the
flaws of early computer benchmarking—small, tightly written benchmark code
resulted in artificially high performance, but the system still performed
poorly when real applications were used. Use benchmarks that make use of (or
simulate) actual programs, or otherwise simulate your true workload.
Obtaining
Benchmarks
Benchmarks have been
around since the earliest computers, and there are now a vast array of
benchmark products to measure all aspects of the PC—as well as measure more
specialized issues, such as networking, real-time systems, and UNIX (or other
operating sys-tem) platforms. Table 4-1 highlights a cross-section of computer
benchmarks for your reference. In many cases, the table includes a URL or FTP
site where you can obtain source code for the benchmark, or download the
complete benchmark program. Today, Ziff Davis and CMP publish a suite of
freeware benchmark utilities that have become standard tools for end users and
technicians alike.
BatteryMarkBatteryMark uses a combination of hardware and software
to measure the battery life of notebook computers under real-world conditions
(the hardware used in BatteryMark is the
same ZDigit II device required by version 1.0). BatteryMark exercises a
different 32-bit software workload engines for processor, disk, and graphics
tasks.
BatteryMark
mixes these workloads together and adds periodic breaks in the work that
reflect the way users pause while working. BatteryMark 2.0 works with Advanced
Power Management (APM) under Windows 95.
NetBenchNetBench is our benchmark test for checking the
performance of net-work file servers. NetBench provides a way to measure,
analyze, and predict how a file server will
handle network file I/O
requests. It monitors the response of the server as multiple clients request
data, and reports the server’s total throughput. To test application servers,
you should use the ServerBench utility instead.
ServerBenchServerBench
is the latest version of Ziff-Davis’ standard benchmark for measuring the
performance of servers in a true client/server environment. Server-Bench
clients make requests of an application that runs on the server—the server’s
ability to service those requests is reported in transactions per second. ServerBench 4.0 runs on IBM’s
OS/2 Warp Server, Microsoft’s Windows NT Server 4.0 (for both Digital Alpha and
x86-compatible processors), Novell’s NetWare 4.11, Sun’s Solaris 2.5 on SPARC, and SCO’s
OpenServer Release 5 and UnixWare 2.1. To test network file servers, use the
NetBench utility instead.
WebBenchWebBench is the Ziff Davis benchmark test for checking
performance of Web-server hardware and software. Standard test suites produce
two overall scores for the server: requests per second and throughput (as
measured in bytes per second). WebBench includes static testing (which involves
only HTML pages), and dynamic testing (including CGI executables, Internet
Server API libraries, and Netscape Server API dynamic link libraries.
JMarkJMark is a suite of 11 synthetic
benchmark tests for evaluating the perfor-mance of Java virtual machines. The
JMark 1.01 suite simulates a number of important tests of Java functionality.
It includes Java versions of a number of
classic benchmark test algorithms, as well as tests designed to measure
graphics performance in a GUI environment. You can download JMark 1.01 from
Ziff Davis, or run the tests online within your browser.
Wintune
97 Wintune for Windows
95/NT is a recent benchmark entry from CMP, the publishers of Windows Magazine.
Wintune 97 is an overall benchmark to measure Windows 95/NT performance. It has
a fast user interface that allows the program to load much faster than the
earlier Wintune 95, and will now support testing of the latest Pentium II
systems. Wintune 97 tests video systems on the fastest new computers at
full-screen resolution.
Troubleshooting
BIOS Beep Codes - AMI BIOS
The AMI BIOS is one of
the most popular in the PC world today, and fortunately is quite consistent in
its use of beep codes, across its many different versions. Please select the
beep pattern you are hearing from the list in the table given below.



Troubleshooting BIOS
Beep Codes - Award BIOS
Award is the other major BIOS
provider today, along with AMI. Award uses by far the fewest beep codes of any
of the BIOS manufacturers.

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