BIOS and CMOS, am i wrong?

[esara]

Hi

Is there any wrong with this statement???

1) I want to understand the BIOS and the CMOS setting.. the BIOS is
the software that will do the POST and also has the bootstrap which
tells the CPU where can find the OS. While the CMOS settng is another
software which is stored in a CMOS chip (different chip of BIOS). The
CMOS setting (sometime called BIOS setting) is basically
configuration values that the BIOS read before starting doing
anything). The CMOS chip need a battery to keep the information stored
inside it.

2) Is it true that the new motherboards have both the BIOS and CMOS
setting in one chip.. so we do not have one chip to store the BIOS and
another chip to store the CMOS setting..


Please correct me if I am wrong.. thanks a lot.

 

[Dave C.]

Hi

Is there any wrong with this statement???

1) I want to understand the BIOS and the CMOS setting.. the BIOS is
the software that will do the POST and also has the bootstrap which
tells the CPU where can find the OS. While the CMOS settng is another
software which is stored in a CMOS chip (different chip of BIOS). The
CMOS setting (sometime called BIOS setting) is basically
configuration values that the BIOS read before starting doing
anything). The CMOS chip need a battery to keep the information stored
inside it.

2) Is it true that the new motherboards have both the BIOS and CMOS
setting in one chip.. so we do not have one chip to store the BIOS and
another chip to store the CMOS setting..


Please correct me if I am wrong.. thanks a lot.

1) is essentially correct. In the BIOS is stored information about all the
various chips on the motherboard, to help the CPU communicate with all the
other components. Also stored in BIOS is the POST program that the CPU will
run to check all those various circuits to make sure that the motherboard
(at least) is working OK. Sometimes the user needs to input information
into BIOS to allow the CPU to use the motherboard to communicate with
hardware components that are not built into the motherboard. Sometimes the
user might want to tweak settings ON the motherboard, as well (such as
overclockers, for a good example) These user defined settings are stored in
CMOS. Most motherboards have their CMOS settings protected with a battery
so that the settings are not lost if you unplug the computer or lose power.

2) depends on the mainboard. A lot of current boards combine BIOS and CMOS
into one chip, so that is true.

 

[-Alby Hewlet]

Sometimes the user needs to input information

into BIOS to allow the CPU ...

user defined settings are stored in CMOS.

Isn't this contradictory? If the user is putting info
into the bios, then what is the point of the CMOS chip?

I thought the bios was programed and that was that.
Didn't you have to buy a new chip in the old days and replace
the one on the mobo, and now you can flash them to update
them. I'm that is so, then how can you input info into the
bios chip?

Alby

 

[Conor]

Isn't this contradictory? If the user is putting info
into the bios, then what is the point of the CMOS chip?

I thought the bios was programed and that was that.
Didn't you have to buy a new chip in the old days and replace
the one on the mobo, and now you can flash them to update
them. I'm that is so, then how can you input info into the
bios chip?

THe BIOS reads settings values stored in the CMOS chip.

 

[Dave C.]

Isn't this contradictory? If the user is putting info
into the bios, then what is the point of the CMOS chip?

BIOS is basic input/output. If all BIOS information could be stored in
BIOS, then CMOS wouldn't be needed. I tend to think of the CMOS settings as
part of the BIOS, even though this is often two different chips. I know
it's confusing. Even I refer to programming the BIOS, when I'm talking
about entering information into CMOS, though that's not technically correct.
Programming the BIOS would be more like flashing to a different version.
-Dave

 

[David Maynard]

BIOS is basic input/output. If all BIOS information could be stored in
BIOS, then CMOS wouldn't be needed. I tend to think of the CMOS settings as
part of the BIOS, even though this is often two different chips. I know
it's confusing. Even I refer to programming the BIOS, when I'm talking
about entering information into CMOS, though that's not technically correct.
Programming the BIOS would be more like flashing to a different version.
-Dave

Everyone is both right and wrong. It depends on the context.

"BIOS" is the Basic Input/Ouput ->System<- and consists of code and values.
You COULD, of course, hard code everything but it's more convenient if some
of the values are variables and, hence, changeable.

How you store those two things, the code and variables, is simply a matter
of technology. I.E. What can do the job.

ROM is fine for code, if you're never going to change it. Well, that might
be a bad idea so we could use EPROMS, except the typical user doesn't have
a U.V. eraser. Flash chips can be electrically reprogrammed a few thousand
times before the failure rate goes way up, and they hold data with no
power, so that is great for 'not very often modified' BIOS code. Note I
said "code," not "the BIOS." What we're doing here is selecting the
'technology' that satisfies the operational requirements but that doesn't
mean 'the chip' is 'the BIOS'. It's only a selected component.

Variables are another matter. They get changed too often for flash (perhaps
not with more reliable flash) so CMOS is used, which, although it requires
power, needs VERY little power so small batteries will keep it alive for
extended periods (and modern motherboards keep it tickled with power even
when 'off', as long as they're plugged in).

So they both store a part of 'the BIOS', code and variables.

The confusion comes from using 'the BIOS" as a kind of slang term. Some
people mean one thing, others another. What's missing is the rest of the
description; like BIOS 'code', or BIOS 'data' (variables).

The point is, you have 'function' and then you have 'how we implemented
it'. For example, I have an old Compaq Deskpro P166MMX machine that has no
code in the 'BIOS chip' (as people tend to call the BIOS code flash storage
medium) for users to modify things. That code resides on a special
diagnostic partition on the hard drive that gets loaded when you push F-10
to do what most folks here call 'go into the BIOS'. It does the same kinds
of things (plus a few more) as the code commonly found in the 'BIOS chip'
of other machines. It's just done differently.

 

[J. Yazel]

Hi

Is there any wrong with this statement???

1) I want to understand the BIOS and the CMOS setting.. the BIOS is
the software that will do the POST and also has the bootstrap which
tells the CPU where can find the OS. While the CMOS settng is another
software which is stored in a CMOS chip (different chip of BIOS). The
CMOS setting (sometime called BIOS setting) is basically
configuration values that the BIOS read before starting doing
anything). The CMOS chip need a battery to keep the information stored
inside it.

2) Is it true that the new motherboards have both the BIOS and CMOS
setting in one chip.. so we do not have one chip to store the BIOS and
another chip to store the CMOS setting..


Please correct me if I am wrong.. thanks a lot.

===========================================================

The BIOS consists of two parts.

1. A ROM (read-only memory) chip (or chips) that contains a program to
boot the system and to handle device requests.

2. A very low power CMOS memory chip (or chips) that contains data
used by the ROM program and needs to be changed by the user.
It is powered by a watch battery.

The two together make up the BIOS.

Jack

 

[Gary Tait]

Hi

Is there any wrong with this statement???

1) I want to understand the BIOS and the CMOS setting.. the BIOS is
the software that will do the POST and also has the bootstrap which
tells the CPU where can find the OS.

Essentially, yes.

While the CMOS settng is another
software which is stored in a CMOS chip (different chip of BIOS).

It is not software, it is simply binary data from CMOS setup.

The
CMOS setting (sometime called BIOS setting) is basically
configuration values that the BIOS read before starting doing
anything). The CMOS chip need a battery to keep the information stored
inside it.

That's it.

2) Is it true that the new motherboards have both the BIOS and CMOS
setting in one chip.. so we do not have one chip to store the BIOS and
another chip to store the CMOS setting..

I haven't heard of it on recent PC desktop systems (or laptops for
that matter), but it is theoretically possible to have settings on a
portion of the Flashrom.

On older desktop systems that a EPROM instead of a flash, the setings
were stored in CMOS ram. In the olden days, they had a special chip
which held the CMOS ram and the RTC. Since then, they have been
integrated into the chipset (in the Southbridge, you will see the
small cylindrical clock crystal beside it).).

 

[Timothy Drouillard]

BIOS
Basic Input Output System

essentially a type of program stored on a chip.(Software)


CMOS
Complimentary Metal Oxide Semiconductor. (Hardware)

The integrated circuit chip itself.


The BIOS is stored in the CMOS chip.

 

[David Maynard]

BIOS
Basic Input Output System

essentially a type of program stored on a chip.(Software)


CMOS
Complimentary Metal Oxide Semiconductor. (Hardware)

The integrated circuit chip itself.

Well, it is a type of integrated circuit and one of it's features is low
power consumption.

The BIOS is stored in the CMOS chip.

If you mean the BIOS code, no. That's usually stored in flash memory these
days. Other places have been ROM, PROM, EPROM, and even the hard drive.

The BIOS parameters are usually stored in a CMOS device because, due to the
very low power consumption of CMOS circuits, a small battery can keep them
alive for extended periods of time while retaining the ability to easily
change them.

 

[Timothy Drouillard]

Well, it is a type of integrated circuit and one of it's features is low
power consumption.

True. I was just simplifying things. Yes there are many type of IC's, CMOS
is just one type. I was just pointing out that CMOS is referring to the chip
the information is being stored in.

If you mean the BIOS code, no. That's usually stored in flash memory these
days. Other places have been ROM, PROM, EPROM, and even the hard drive.

The BIOS parameters are usually stored in a CMOS device because, due to the
very low power consumption of CMOS circuits, a small battery can keep them
alive for extended periods of time while retaining the ability to easily
change them.

Again you are correct, and again, I was just trying to keep things simple.

I was simply pointing out that too many people use the terms CMOS and BIOS
interchangably, when they are actually two different things. The BIOS
settings that people change in their motherboard setups are stored in a CMOS
chip on the motherboard.

 

[Gary Tait]

Isn't this contradictory? If the user is putting info
into the bios, then what is the point of the CMOS chip?

The BIOS runs the little program you enter the informationinto. The
program compiles the data and stores it in the CMOS or other storage.

I thought the bios was programed and that was that.
Didn't you have to buy a new chip in the old days and replace
the one on the mobo, and now you can flash them to update
them. I'm that is so, then how can you input info into the
bios chip?

Flash chips can come with several data areas;
a bootblock (which is often protected, and keeps enough smarts to boot
off of a floppy to flash the main program section), a main program
section, and one or two auxillary areas, which can be independantly
programmed without harm to the other areas.
With that, the setup brogram would write to one of the auxillary areas
instead of CMOS ram, which would be relegated to just the RTC.