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BIOS Setup

Changing the BIOS configuration is one of those things that novice computer users are sometimes warned against, as being only slightly less hazardous than tinkering with the Registry. It’s true that incorrect BIOS settings can keep a computer from functioning properly, but it’s also true that a competent technician needs to know how to configure the BIOS (without creating disaster), and that’s what this tech tip is about.

First we should clarify terms, because we are not actually changing the contents of the BIOS chip. The BIOS chip itself contains a program that is hard-wired in, and while it’s possible to ‘flash’ some BIOS chips, which electronically replaces the entire contents at once, it’s not possible to edit individual lines of the BIOS code in the chip. Unless it’s flashed, the BIOS will keep its contents intact essentially forever.

What we are really changing during a ‘BIOS setup’ are the contents of the CMOS chip. CMOS is a type of slow memory chip that requires very little power, usually supplied by a small, long-life battery. This makes it ideal to save information that might need to be changed occasionally but also needs to be safely stored while the computer is off, because the BIOS will use that information at boot-up. If you were to store a computer unplugged for a few years until the battery ran down, you would find that all of the data stored in the CMOS chip was gone.

Part of the programming stored in the BIOS is a routine that lets you edit the information in the CMOS chip, and that routine is commonly called the BIOS Setup program. You can access this program by hitting the correct key during the boot-up process. Unfortunately there is no standard for which key to press. One of my computers uses the Del key, and another one uses the F2 key. You have to read the screen prompts early in the boot process, looking for one that says “Press the x key for setup”, or something similar. Then you need to press that key when it first appears, or soon after. By the time the prompt disappears, it’s definitely too late.

If you press the right key, and in time, the BIOS will discontinue booting and will open the BIOS setup program, which displays a series of menus and submenus for the various parameters that you can change. Because the operating system hasn’t loaded yet, there will be no fancy interface and no mouse control. Navigate the menus using the arrow keys, using Enter to select something and the Esc key to back up.

Although the navigation is fairly standard, every BIOS version will have a different menu setup and a different selection of items that can be edited. Two of the menu items are to exit the setup and save the changes, or to exit without saving the changes. When you do either of these, the boot-up process will continue where it left off.

Following is a sampling of the values that you can access and edit from the setup program. Keep in mind that any individual machine may have some of these and not others, and will probably have some options not listed here. Newer systems will generally have more options for configuration. They are also more likely to collect data automatically from the system hardware, in which case you should think twice before changing it. On older systems, it was often necessary to manually enter the configuration data when adding memory, peripheral devices etc.

Clock speeds – Some setups allow you to change just the master clock, and some let you tweak the clock speeds individually for the CPU, bus and RAM. This feature is loved by gamers who over-clock by jacking up the clock speeds, which is an excellent way to invite system errors, as well as voiding the warranty and possibly burning out your CPU chip.

Hard drive parameters – The cylinder head and sector values can be monitored, and sometimes edited. You can also monitor the primary/secondary and master/slave arrangement of the IDE drives.

Boot sequence – The usual sequence has the BIOS look for an operating system first at the floppy drive, then the hard drive and last at the CD-ROM drive, and the system will boot to the first OS it finds. This works well at the factory, but if you want to boot from a CD, for instance to run the Micro-Scope diagnostic, then the sequence needs to be changed to check the CD before the hard drive, which already has a resident OS.

ROM shadowing – RAM is faster than ROM, so copying ROM contents into RAM normally provides better performance. This option is enabled or disabled in BIOS setup.

Power management – Edit the conditions under which a system will go into hibernation, and the events that can wake it up again.

Caching – Caching can be enabled or disabled, for the CPU and sometimes for video RAM as well. One occasion when you might want to turn off CPU caching is during RAM testing. Some memory diagnostics do not flush the cache, so the test is actually looking at cache rather than RAM. For diagnostics that do flush the cache, disabling the cache will allow the tests to run faster.

Voltage control or monitoring – Some BIOS versions let you tweak the various system voltages. Some just let you monitor them, and some do neither. Like over-clocking, changing voltages is something that should be approached with caution.

Passwords – Some systems let you change the administrator and user passwords in the setup program. Some do not, and require you to ‘drain’ the CMOS by disconnecting or shorting across the battery before a new password can be entered. Of course, all of the other CMOS data will be deleted too. Yet another reason not to forget your password.

Date/time – The system’s RTC (Real-Time Clock) stores its values in CMOS, and is often incorporated into the same chip. The date/time values provide a reference for the OS and for many applications. Remember the Y2K hoopla a few years ago? Part of the problem was that many computers had ‘19’ hard-wired into the BIOS and only allowed you to edit the last two digits of the year.

Memory – Older systems sometimes required the user to enter the amount of memory the system was supposed to detect. Newer PCs will detect the amount of installed RAM automatically, and will let you view it but not always edit it.

PC Health – This is a monitor-only feature found in many new systems, which displays system and CPU temperature, fan speeds and sometimes other data, depending on the manufacturer. Whatever PC Health information is available will also be reported under the Utilities menu of the Micro-Scope program.

Well, that’s BIOS setup in a nutshell. There is one other thing that we should mention. Because computers have been known to fail on rare occasions, it can be quite handy to have the more critical CMOS information and settings written down somewhere on a piece of paper. And this paper record should be updated whenever major changes are being made to a system.

Disclaimer - The Micro 2000 Tech Tip is a free service providing information only. While we use reasonable care to see that this information is correct, we do not guarantee it for accuracy, completeness or fitness for a particular purpose. Micro 2000, Inc. shall not be liable for damages of any kind in connection with the use or misuse of this information.