BIOS Explained

Every computer has BIOS (Basic Input/Output System) that runs a diagnostic test each time the computer boots up. Before it launches the operating system, the BIOS checks to make sure all the hardware is working. It then works with the computer’s hardware components with the operating system.

The BIOS is stored in a ROM chip that is on your motherboard. PCs built in the past couple of years use flash BIOS, which means the BIOS is on a flash ROM chip. These chips are more easily updated than regular ROM chips. ROM is an ideal place for the BIOS because it is on a safe place on the motherboard where it is not vulnerable to drive failures. However, because ROM is slower than RAM, newer computers copy the BIOS from ROM to RAM during the startup process. This process is called shadowing, and it improves the performance of your PC.

The diagnostic test that the BIOS performs is a POST (power on self test) for the keyboard, drives, ports, chips, and all other components in the system to make sure they are working correctly. You can see and hear the BIOS performing this POST during your system’s startup process. One long beep means the BIOS successfully completed all the hardware tests. A combination of shorter beeps indicates a number of different errors. (See the Common Error Messages section for more information.) A healthy system BIOS will display information about the computer, including the amount of RAM, the number of drives, and the type of processor. If the BIOS detects a hardware problem, it will halt and display a text error messages on-screen. When this happens, you need to know how to fix or adjust your BIOS.

Time For A Change. When you have a BIOS problem, you will probably need to make changes in your BIOS’ settings. Even though this is easy and takes only a few minutes, making the wrong change can wreak havoc on your system. A problematic setting could prevent your computer from rebooting. Be very cautious and change nothing that isn’t necessary.

To change your BIOS settings, you must enter the computer’s CMOS (complementary metal-oxide semiconductor) setup screen during the startup process. CMOS is a small chip that stores information about your particular system and its devices.

To find the CMOS setup screen, reboot your computer. Start by pressing a certain keyboard combination during startup. You should see a line of text at the bottom of the display that tells you which key or keys you need to press to enter the CMOS or Setup area. (NOTE: You may have to completely shut down your system and turn it back on to see what this key combination is.) Most systems use ESC, DELETE, F1, F2, CTRL-ESC, or CTRL-ALT-ESC. If the screen doesn’t indicate which keys to press, the computer’s documentation should do so.

The screen will display several menus, each with rows and columns displaying options for changing dozens of settings. The wording is different according to each system and BIOS manufacturer. Here are some common settings and their definitions, although the names might be different in your CMOS:

System Time/Date: Lets you change the time and date displayed in the lower right corner of Windows.

Security or Password Protection: Lets you set a password for accessing the computer. Because Windows’ password screen is easy to avoid (you can press ESC or click Cancel), this BIOS option provides tighter security and requires you to enter the password before the system ever boots. Be sure to write down your new password because if you forget, it will take a great deal of work to access your computer again. (See the “Password Pains” sidebar for information on what to do if you do forget this password.)

Enable Number Lock: This setting is essential for anyone who uses the numbers on the 10-key section on the far right of the keyboard. However, if you don’t use the number pad, and you don’t like the little green light that comes on every time you boot up—the one that tells you the number lock is enabled—turn off this setting. (NOTE: You might find this option under the Start Options category.)

Memory: Because BIOS is on a relatively slow ROM chip, this setting lets you direct BIOS to shadow with RAM or a different memory source. (NOTE: You might find this option under the Advanced Setup category.)

Boot Sequence: This setting determines the order in which the BIOS reads drives in search of startup instructions. The BIOS traditionally begins with the hard drive. Change this setting to boot your machine from a CD-ROM or Zip disk when you reinstall the OS or use a boot diskette.

Exit: When you are ready to leave CMOS, you will have the options of saving the changes, discarding the changes, or restoring the system default settings. If you made changes, your computer will restart to put the new settings into effect. If you suspect that you’ve made a problematic change, exit without saving.

Upgrade. Newer computers rarely, if ever, need to have their BIOSes upgraded to work with new equipment. Both software and hardware upgrades typically come with drivers, software you install so the devices can work with your computer. Older computers, on the other hand, might need a BIOS upgrade to understand new hardware and software installed on the system. An upgrade will also have the ability to correct newly detected bugs.

To upgrade an old BIOS, start by reading the screen during startup and looking for the name of the BIOS manufacturer. If you don’t see the name of your manufacturer, go into the CMOS setup (see the above instructions). The very top of the CMOS screen should identify the BIOS maker. The largest manufacturers are Acer Labs, AMI (American Megatrends), Microid Research (Mr. BIOS), Phoenix Technologies, and Winbond.

You can also determine the manufacturer in Windows. In Windows 98 and Me, click the Start button, Programs, Accessories, System Tools, and then System Information. At the top of the left column, click System Summary. Then, you should see the BIOS Version line.

Next, find the version number of your present BIOS (if you can). This is a long string of digits and letters that flashes at the top of the screen during the first moments of start up. Press the PAUSE key to freeze the screen while you record the number. If you can find it, go back to the CMOS setup and find the BIOS date.

Go to the BIOS manufacturer’s Web site and find a BIOS upgrade program for your system. Look under a link called Free Downloads or Technical Support, then follow the instructions specific to your model PC. Upgrading BIOS can backfire if you install a version that is not compatible with your system. Thus, upgrade only when you are sure it is necessary and then do so carefully, double-checking that you are downloading the proper update. You may want to contact technical support before you install the file.

Be very careful once you enter the CMOS setup screen and start making changes. Incorrect settings could prevent the computer from rebooting.

Copy the program, including the update and utility, onto a diskette. Restart the computer with the diskette in the drive. The program should erase the old BIOS settings and install new ones. In addition, follow any manufacturer instructions for installing the software.

Fix. If you’ve tried troubleshooting a piece of hardware to no avail, the problem might be hidden in your BIOS settings. To find out, enter CMOS by pressing the correct keyboard combination during the startup process, as described above. Try these steps to correct poorly set BIOS. ( NOTE: The names for each setting might be different in your CMOS and/or you may not have some of these settings.)

The system is not detecting a new drive. Go to a CMOS setting called Drive Configuration, Hard Disk Settings, or even Devices And I/O Ports. It lets you configure the hard drives, CD-ROM drives, and diskette drives. PCs made in the past few years come with an automatic-detection program that enters configuration data into CMOS. If your system is older than that, or if you installed a drive your system is not detecting, enter the drive information manually to prompt your system to detect it. You do this in CMOS, where your drive information is located. This area is often called Drive Configuration, Hard Disk Settings, or something along those lines. There will be an option where you can choose between manual detection and automatic detection.

Diskette drive problems. If you are encountering mysterious diskette drive problems, go into the Diskette Disk or Devices And I/O Ports settings. Make sure it shows the type of drive in your A and B ports. For example, if your port has a drive for a 3.5-inch diskette or a 1.44MB diskette, the BIOS setting should reflect that information. If your computer is refusing to save data onto a diskette, make sure the Floppy Read Only setting is disabled. This setting prevents you from writing data to a diskette.

Trouble installing a mouse. If you’ve plugged in a mouse or other serial device and it is not responding, go to Serial Port Settings. This setting might have the port turned off or labeled as Disabled.

Printer woes. A new printer that is running slowly or refuses to work at all might be the victim of the wrong mode setting of its parallel port. Find a group of settings called Parallel Port or Parallel Port Setup. They will give you choice of four modes that determine the speed and transmission capabilities of the parallel-port connection: standard, bi-directional, ECP (extended capabilities port), or EPP (enhanced parallel port). Printers made several years ago use the slower, standard mode and may not work if plugged into a port set to a fast mode. Similarly, new printers may not function unless you set their ports to ECP.

Common Error Messages. Many other common BIOS problems will probably disturb your PC at one time or another. Many of these quirks will happen during the startup process. If the BIOS detects a difficulty during startup, the screen will display an error message or the system speaker will emit a combination of beeps to help you narrow down the irregularity. The computer’s documentation and BIOS manufacturer’s Web site should list dozens of codes and their meanings. Here, we translate common beep codes and error messages, although they may not be the same for your system. ( NOTE: To fix any of these problems, you may need to check with your computer’s BIOS manufacturer.)

CMOS Checksum Error —BIOS thinks a virus, dying battery, or other anomaly has changed a CMOS setting without your knowledge. This can happen when you flash the BIOS. Go into CMOS, restore the old settings, and reboot the computer. If the error does not recur, run an antivirus program just in case a bug has changed the CMOS settings. If the error does recur, replace the battery. This battery is important because it keeps the BIOS safe from power outages. Just open up the case and replace the battery. Don’t worry about losing information; it takes some time before the battery drains. However, you should replace the battery as quickly as possible.

Battery State Low—You don’t need to go into CMOS because this error specifies the problem. Open the case and replace the battery.

Diskette Drive A Error or Incorrect Drive A Type—Cables connected to Drive A might be loose. Turn off the computer, ground yourself, open up the case, and tighten cables leading to Drive A. If the message comes back when you reboot, go into CMOS to confirm you have the drive properly configured.

Keyboard Error— There is probably a loose cable between the keyboard and CPU. Tighten every cable and reboot your system. “Keyboard Error NN” indicates a key is stuck.

Diskette Boot Failure—If you’re trying to boot up from a diskette, the BIOS thinks the diskette is corrupted or has a virus. Try to boot up another computer with this diskette to learn whether it’s truly corrupted or whether your computer is to blame.

Display Switch Not Proper—A video switch (physical circuitry) on the motherboard should be set to color, but it is set to monochrome or vice versa. Turn off the machine, change the switch on the motherboard, and reboot.

KB/Interface Error—The keyboard connector is malfunctioning.

FDD Controller Failure—BIOS cannot communicate with the diskette drive controller.

HDD Controller Failure—BIOS cannot communicate with the hard drive controller.

DMA Error—The Direct Memory Access controller is malfunctioning.

One short beep—There is a problem with the memory refresh circuits on the motherboard.

Five short beeps—The CPU is indicating an error.

Eight short beeps—The video card (also called graphics card or video adapter) is missing, is not responding to the BIOS POST, or has faulty memory.

One long and three short beeps—The monitor or video RAM has failed. If you confirm these devices are functioning properly, check other parts of the video system.

Don’t Be Afraid; Be Careful. If you have a BIOS error or BIOS-related problems, don’t be afraid to try to fix the problem. If you ever foul up your system even more, reboot it while holding down the key or keys used to enter setup. This bypasses extended CMOS settings and is the first step in getting your PC up and running again. Once you get to the Setup menu, you can reload the original factory settings by choosing Load Values From CMOS. However, remember that changes you have made to the BIOS since you bought the PC, including adding storage devices, will not be reflected in these values. In addition, sometimes you can make changes that will prevent your system from rebooting again, so just be careful.

by Raya Tahan

Password Pains

Many users take advantage of the extra security settings offered in the BIOS (Basic Input/Output System). Although a computer thief or unscrupulous co-worker could easily get past your Windows password, he would have infinitely more difficulty cracking a password set in the BIOS. The downside to having this higher level of security is you will lock out yourself if you forget your password.

A CMOS (complementary metal-oxide semiconductor)-set password will cause the system to prompt you for the password during every startup, before it launches the operating system. If you lose your password or it suddenly does not work, you could have a big problem.

The first thing to do is to try to find a default or backdoor password that works with your brand of BIOS. Most major BIOS manufacturers program their chips to work with certain words as a password. Try typing the name of the manufacturer in as your password. For example, your might try “AMI,” “Award,” or “Mr Bios.” Some manufacturers set the default password to be a common word such as, “bios,” “setup,” “cmos,” “password,” “sw,” “SW,” or “BIOSTAR.”

If those don’t work, contact the maker of your PC, motherboard, and BIOS to ask whether a default password exists. If so, they should reveal it to you when you provide a receipt to show you own the PC.

If the manufacturer will not help, you must open up the case and make physical changes to the motherboard. Always unplug the computer and ground yourself by touching metal.

The motherboard manual might list a jumper that clears the present CMOS password. If this is the case, just reset the jumper and boot up your personal computer.

If your motherboard lacks this setting, you probably have to use a different motherboard jumper that resets the entire contents of the CMOS program. Find a jumper that has three pins adjacent to the battery. Reset CMOS by moving the jumper from 1-2 to 2-3, or from 2-3 to 1-2. If you had gone into CMOS and manually configured the date, time, disk drive detection, and other settings, you’ll have to do that all over again once you can get into your computer.

If your motherboard has no reset jumper whatsoever, your last resort is to erase the BIOS settings by physically pulling the CMOS battery off the motherboard. It’s a small, round battery, usually sitting near the power connector. Remove it from the board and keep it off for several hours because it takes that long for the charge to drain out of the CMOS circuits.

If your CMOS battery is soldered down to the motherboard, you should probably have a technician replace it.

Note:  This compilation of information are from various sources.  All credit due to its authors.
XP Support- 01/01/2005 12:42 AM - Home Page WinXP
© Copyright Kelly Theriot MS-MVP(DTS) 2005. All rights reserved.