Ken Blake wrote <<These are setting that are kept in a special memory chip
on the motherboard. They are the basic hardware settings on the system, and
contain the time and date, among other things. The battery we've been
talking about keeps all of those settings correct, as well as the time and
date.>>
Perhaps this needs fleshing out a bit. When a computer is off it is nothing
more than a collection of metal, plastic etc. It doesn't 'know' anything
about anything. except the CMOS (complementary metal oxide semiconductor).
This chip stores the very basic parameters of the computer. These include
the date, time and a technical description of the such things as the hard
disk drive - and many others. Obviously when the computer is not connected
to the mains it needs something to maintain this information and that is the
job of the CMOS battery. Now CMOS batteries like any other have a life. If
the computer is stored unused (in a shop or whilst you are on a long
holiday) the power is being drained from the battery. A charge in a CMOS
battery can last for, say, 3 or 4 years. When you turn on you computer it
first looks to information in the CMOS to tell itself what it is before
looking to the BIOS and then the hard disk to load the operating system
(Windows) and other software. Think of it as a bit like you waking up on
the first morning of a holiday and having to work out why the sun is now
coming in from the opposite direction etc before you try to work out what
you will be doing that day.
Regards.
Bill Ridgeway
Computer Solutions