keyboard BIOS

[PeteSchiffer]

I've got an old motherboard lying around. It's got a chip on it labelled "AMI keyboard BIOS". Do keyboards still have a controller chip? This one is quite large, about two inches long. Perhaps they are smaller now.

Pete

[Beno]

Yes keyboards do have a chip in them. When you type out letters from your keyboard, a little chip in the keyboard (which can be quite long!!) notices which key has been pressed and stores this in the chips registers (temp memory for chips). The bios routines along with the system CPU checks the registers in the keyboard chip periodically for what is known as the scan code.

The scan code is a unique combination of 0's and 1's that the bios routines recognize. Once the system CPU has this information, thanks to the help of the bios routines, it can then pass that information up through to the operating system and then to the specific program such as Internet Explorer or MS Word etc etc

Hope that makes some sense to you!

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"Don't stop till you get enough"

[PeteSchiffer]

Beno,

Thanks for the reply.

My error, but it has prompted a follow up. I asked if keyboards still had a controller chip, I meant to ask "do motherboards still have a controller chip?"

Anyway, it seems that keyboards have a controller chip in the keyboard, is that what I am seeing on this motherboard? i.e. in the passage of time has the chip moved from the mobo to the keyboard?

Or are there two chips, one on the mobo and one in the keyboard these days?

And these chips are some kind of non-volatile ROM?

Pete

[Beno]

Hey Pete,

Didn't recognize you were from Aus - me too!!

There has always been a controller chip in the keyboard. It is called the 8042 chip and hasn't really changed at all because keyboards are well - keyboards, simple devices!.

There is also a chip on the motherboard that acts as a controller - two actually. This group of chips is called the "Chipset". The two chips are called the northbridge chip and the southbridge chip. They help the CPU out by serving as assistants. They do tasks such as accessing devices and memory and listen to requests from devices etc. The Northbridge chip interacts directly with the video card in your computer so as to not bog down the CPU.

The chip itself is not ROM or RAM, simply a chip. Your thinking of the CMOS chip which holds basic programs that the CPU and Op.Sys use to access the hardware. The cmos chip is as you have stated - Non-volatile RAM. It is in fact RAM but is called non-volatile because there is a battery that continually supplies the CMOS with power, even when the machine is turned off. It holds the data and also keeps the date and clock ticking!

Hope that helps?!

Beno

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"Don't stop till you get enough"

[PeteSchiffer]

Hi again Beno,

I'm in Redcliffe, cool breeze here today.

Thanks for the reply.

I'm getting there, but I'm definitely confused by these three terms: firmware, ROM and chip.

I know that firmware is classically described as software on a chip. But that doesn't say much really.

Taking the keyboard example.
There's the controller chip in the keyboard itself. I kind of understand its function (says what kind of keyboard it is, accepts information from the user and then passes it on to the next whatever it is?). Is this keyboard controller chip firmware?

Then there isthe keyboard controller chip on the motherboard, which from your explanation are resident in either the north or south bridge, along with controller chips for other devices. Are these two controller chips (the north and south bridge) firmware or what?

Or are things like the BIOS ROM and the chipset both firmware, just different kinds of firmware.

Nice to meet you,

Pete

[This message has been edited by PeteSchiffer (edited 02-15-2002).]