A+ Certification: How to Pass Your Exams

Last Updated 2/3/2009 3:42:58 PM

Abstract

This chapter is targeted primarily at someone studying for the A+ Certification exam. You will learn how to recognize and interpret the meaning of common error codes and startup messages from the book sequence, and identify steps to correct the problem; recognize Windows-specific printing problems and identify the procedures for correcting them; recognize common software problems and how to resolve them; and identify concepts relating to viruses, virus types, dangers, systems, and how to protect against them. The chapter ends with a quiz and suggested activities.

While repairing PCs, you will need to be able to recognize the difference between a hardware error and a software error. You will also need to be able to tell what is broken, based on certain indicators. This chapter explores some of the common software errors encountered while booting or during normal operation and ways to correct the errors. We also cover what a virus is and does and how to recognize and remove a virus.

Upon completion of this chapter, you will be able to

Recognize and interpret the meaning of common error codes and startup messages from the boot sequence, and identify steps to correct the problem.
Recognize Windows-specific printing problems and identify the procedures for correcting them.
Recognize common software problems and how to resolve them.
Identify concepts relating to viruses, virus types, dangers, systems, and how to protect against them.

STARTUP MESSAGES

The first messages you will likely see when troubleshooting a PC are startup messages. They give a good indication of what might be wrong with the system, but several of the messages indicate a problem that could relate either to hardware or to software. Some of the more common messages you may see are listed in Table 13.1.

Other problems and indications include:

Master boot record — If the master boot record is missing, the system will not be able to find the boot files and initiate the software boot sequence.
Partition table — If the partition is missing or damaged, the system will not be able to find the boot files. Depending on the operating system, the error messages may be the same as with a damaged master boot record. Use Fdisk to view the partition table.
Active partition — When the system boots, the BIOS searches for the active partition to initiate the software boot sequence. If no active partition is set, the system does not initiate the boot sequence. Use Fdisk to configure the active partition.
Operating system — If the OS is missing, the error will indicate a bad or missing OS. Follow the hard disk troubleshooting procedure to help determine the cause.

MS-DOS

MS-DOS problems can be easy to fix, but at times they can be extremely hard to identify and resolve. Follow these steps when trying to repair a problem that appears to be related to MS-DOS.

Verify information stored in CMOS. The hard drive must be properly defined, or the BIOS will not be able to find the operating system and hand the boot process over to MS-DOS.
Use the Fdisk utility to ensure that the partition information is correctly configured and the proper partition is defined as Active.
Use the Scandisk utility (MS-DOS 6.x) to verify the disk and files on the disk.
Use the Defrag utility (MS-DOS 6.x) to defragment the disk drive. Scandisk and Defrag may not resolve the problem you are troubleshooting, but they are very good general preventive maintenance steps.
Use the Mem utility (MS-DOS 6.x) with the /c switch to verify the memory’s configuration and that all drivers listed in the Config.sys and Autoexec.bat are loaded.

Fdisk
As mentioned above, one of the MS-DOS utilities you can use is Fdisk. The MBR could be made corrupt by a virus program or hardware error, and if it is corrupt, the system will not be able to boot. To replace or rewrite the MBR information, use the Fdisk utility with the MBR switch (Fdisk /mbr).

If the partition information is corrupt or missing, use the Fdisk utility to recreate the partitions. When the partition table information is recreated, all information stored on the hard disk is lost as the pointers to the information are cleared. If the wrong partition is marked Active or no partitions are marked Active, use the Fdisk utility to mark the proper partition as Active.

Format

With the Format utility, you can perform a high-level format on a drive. When a drive is formatted, all information on the drive is lost.

Sys

The Sys utility writes Io.sys, Msdos.sys, and Command.com back to the drive. Io.sys and Msdos.sys must be copied to the proper location on the drive. If the files are placed on the drive with the Copy utility, the files might not be located in the proper place. The Sys utility was specifically developed to copy Io.sys and Msdos.sys to the proper location.

Scandisk

The Scandisk utility replaces the Chkdsk utility and is used to test the surface of the disk drive. Any clusters that are found to be unreliable are marked as bad. If information is located on a bad spot, Scandisk attempts to relocate the information. Using the Format utility with the /c switch will retest spots that have been marked bad on previous scans.

Mem

You can use the Mem utility to view the memory configuration and the drivers that are loaded. Use the /c switch to see a complete list of loaded drivers. Typically, you will need to use the ½more (pipe-more) option to pause the screen at each page.

WINDOWS 3.x

Windows 3.x can suffer from startup errors, which cause it to fail to launch properly, and General Protection Fault (GPF) failures. Windows 3.1 has some utilities that can help troubleshoot the startup process. You can make the system start in one of several configurations by adding a switch to the Win command. The switches include

/3 — Starts Windows in 386 enhanced mode.
/s — Starts Windows in standard mode.
/b — Creates Bootlog.txt, a file that records system messages generated during system startup (boot).
/d — Starts Windows in a mode you can use for troubleshooting when Windows does not start correctly.
:F — Turns off 32-bit disk access. Equivalent to the System.ini setting 32BitDiskAccess=False.
:S — Specifies that Windows should not use ROM address space between F000:0000 and 1 MB for a break point. Equivalent to System.ini setting SystemROMBreakPoint=False.
:V — Specifies that the ROM routine will handle interrupts from the hard disk controller. Equivalent to System.ini setting VirtualHDIRQ=False.
:X — Excludes all the adapter area from the range of memory that Windows scans to find unused space. Equivalent to System.ini file setting EMMExclude=A000-FFFF.

By using the /b switch, Windows 3.1 records information about the startup process in a file called Bootlog.txt, located in the Windows 3.1 system directory. By default, this directory is C:\ Windows. You can use the MS-DOS Edit utility to view the Bootlog.txt file.

Dr. Watson is a debug tool that records system error information and can be used in troubleshooting. You can add Dr. Watson to the Startup group so that Dr. Watson will be active each time Windows is initialized.

Note: You can use Sysedit to view and modify the Config.sys, Autoexec.bat, Sustem.ini, and Win.ini files. If you don’t use Sysedit, use Notepad. These are the four major system files MS-DOS and Windows use to configure the user environment.

Common Indications and Failures

Some of the more common Windows 3.x-related failures are listed in Table 13.2.

Another error that you may come across is the General Protection Fault (GPF) error. It is one of the more difficult problems to troubleshoot. A GPF occurs when another application or driver overwrites one application or driver’s memory space, causing a memory conflict. Two steps to troubleshoot this type of problem are:

Look for the last application or device installed. If it was installed within the last two or three weeks, try uninstalling or disabling that device or application; then test for proper operation.
If nothing has been installed recently, reseat the RAM, check the fans for proper cooling, and retest. Test for proper operation. If failure continues, start Windows without any of the startup items running by holding the Shift key while starting Windows.

Note: If a program is loading from the Startup group in Windows 3.x, you can held the Shift key during the boot processg to bypass the Startup group.

VIRUS PROBLEMS

Virus problems can have many indications, from certain programs not working properly to the computer not booting up. If anything unusual occurs on the system, run the most current virus detection software available. Ask the user if any new files have been loaded on the system lately. Two of the more popular virus detection software packages available are made by McAfee and Symantec (Norton Anti-Virus).

Two common virus types that can infect MS-DOS, Windows 3.x, Windows 95, and Windows 98 are the Command.com and boot sector viruses. Command.com viruses corrupt the Command.com file that MS-DOS and Windows operating systems use when booting. You should see “Bad or missing command interpreter” if the Command.com file is corrupt. If you verify that the Command.com file is actually on your hard drive or floppy disk, but you still get that message, suspect a virus.

Boot sector viruses prevent the system from booting via the master boot record. If the MBR is damaged, the operating system can’t load. Usually, these viruses can be cleared with the command Fdisk /MBR (as previously mentioned). Modern virus scanners can detect Command.com and MBR viruses. In addition, virus scanners protect from many other viruses. Table 13.3 lists examples of Virus protection software available.

Note: Since new viruses are created continually, it is wise to keep with the latest information on viruses. One organization that provides updates on virus problems is CERT, which is located at http://www.Cert.org. You can sign up for free updates on this site

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