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BOOT CAMP 133
BEGINNERS GUIDE TO BIOS – Part 1
The Basic Input Output System or ‘BIOS’ may not sound
particularly interesting but it is arguably the single most important piece of
software on your PC. The BIOS’s job is to initialise and configure a collection
of inert electronic and electromechanical components and turn them into a
working computer, ready to load and use the operating system, which for most of
us is Windows. This week we’ll look at what the BIOS program does, how it works
and some common problems; next week we’ll delve a little deeper into its inner
workings and consider how it can be used to change your PC’s behaviour and
possibly improve its performance.
The BIOS program resides in a read-only memory or ROM
microchip on the PC’s motherboard. It is stored in a chip because when it is
powered up your PC’s processor or CPU has no idea of what devices are attached
to the system, let alone how to use them, so it would be pointless storing such
a program on the hard disc drive. This also means the computer can still ‘boot
up’, even if the disc drive is faulty, or absent.
On early PCs the BIOS program was a fixed entity and the only
way to alter it was to replace the ROM chip or the entire motherboard. Nowadays
most BIOS programs are held in an EPROM chip (see Jargon Filter) and it is
possible to update or change the information, to accommodate new developments in
hardware and software. However this is a mixed blessing since virus programs
have been created that can infiltrate or corrupt the BIOS, turning a PC into a
useless pile of junk. More importantly even minor changes to the BIOS program
can have major consequences to your PCs well being so we’ll begin with a general
warning to look but don’t touch, and never fiddle with the BIOS on your PC
unless you know exactly what you are doing.
Configuration settings for your PC are stored in a CMOS type
memory chip (see Jargon Filter), unlike a ROM or EPROM, which retains data when
the power is removed; CMOS memory is ‘volatile’ so the chip has to be
permanently powered. This is done with a backup battery, which also maintains
the PC’s internal clock. Backup batteries generally last around five years; the
first sign that it is failing is usually erratic timekeeping, but if after
switch-on you see an error message ‘CMOS checksum invalid’ or ‘Invalid
configuration, run Setup’, then that is a sure sign that the battery needs
replacing. It’s not usually a difficult or expensive job but if you’ve any
doubts have it seen to by an engineer.
One of the BIOS program’s most important jobs is to carry out
a series of diagnostic checks on the main motherboard components, including the
RAM memory chips and input/output devices; this is called the Power On Self Test
or POST and it happens a few seconds after you’ve switched on. Normally the POST
goes smoothly, on many PCs you’ll hear a single short bleep from the internal
speaker confirming that all’s well, and Windows will begin loading. However, if
you hear more than one bleep, a continuous tone or a repeated sequence of
bleeps, that is a sure sign of trouble.
The number and pattern of bleeps or error code indicates the
nature of the fault but this varies significantly according to the make and type
of BIOS. You can find out more by first noting the name and version of your PCs
BIOS – it appears on the monitor screen for a few moments after switch-on -- and
then consulting the appropriate manufacturer’s web site, or by visiting: http://sysopt.earthweb.com/biosbmc.html.
This is one of several sites that lists the most common types of error code by
manufacturer. Most faults are well beyond the scope of the average PC user but
occasionally an error code points to an unseated adaptor card or loose
connecting cable, which the more intrepid amongst you can attempt to remedy.
POST error messages often appear following a major upgrade,
replacing a hard drive, adding extra memory or changing the CPU. Since there are
so many possibilities we can only generalise but more often than not the
solution is to update the PCs BIOS. You may be lucky and find a reference to the
problem in the new hardware’s manual or troubleshooting guide, if not check the
company’s web site, and the BIOS manufacturer’s web site for details of any
known problems and solutions.
We’ll round off by showing how to access your PC’s BIOS
program, and remember, don’t touch anything! The precise method varies but on
most BIOS’s a message appears on the screen at switch on, saying something like
‘Press DEL to enter SETUP’, or a combination of keys. Do so and you will see the
BIOS main menu. Your mouse probably won’t be working so selections have to be
made using the keyboard arrow up/down keys; to look at a particular menu
highlight the entry and press Return. Once an item is selected changes are
usually made with the Page Up/down keys, and confirmed with the Return key. Do
not make any changes or you will regret it! When you’ve finished having a look
around return to the main menu by pressing the Esc key and quit the BIOS by
selecting the item ‘Exit without saving changes’ or words to that effect. You
may be prompted to confirm your decision; i.e. ‘Are you sure?’ in which case
enter ‘Y’ for yes, and press Return. The PC should now continue to load Windows
as normal.
Next week – Inside the BIOS
JARGON FILTER
CMOS
Complimentary Metal Oxide Semiconductor – a type of
‘volatile’ memory chip that retains information whilst it is powered
CPU
Central Processor Unit – the main microprocessor chip (i.e.
Pentium etc.) in a PC
ROM/PROM/EPROM
Read Only Memory/Programmable Read only Memory/Erasable
Programmable Read only Memory; a ‘non volatile’ memory chip that retains
information when the power is removed. Information in ROMs and PROMs is fixed
whilst an EPROM can be re-programmed with new data
TOP TIP
Here’s another one of those ‘secret’ Windows 98 utilities.
It’s called Hardware Info and it carries out a comprehensive check on driver
files and the hardware attached to the PC, flagging up potential problems. Error
information is displayed in red, and warnings in blue. To start Hardware Info go
to Run on the Start menu and type ‘hwinfo /ui’ (omitting the inverted commas of
course), and then click OK. It only takes a few seconds after which the report
appears. Check through it looking for any red or blue highlights, which may
indicate a problem, or trouble brewing, and might require further investigation.
If you know a thing or two about PCs you may want to have a look at the
alternative reports on the View menu. If your PC and hardware is behaving
normally it’s probably a good idea to leave well alone, but take note of any
warnings and save your Hwinfo file for future reference or to show to an
engineer.
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