is CMOS = BIOS in motherboard?

Hello, fixpc! You wrote on Thu, 2 Mar 2006 20:45:14 +0800:

f> is CMOS = BIOS in motherboard?

f> TIA

Yes, the BIOS (Basic Input Output System) is the first level operating system which is typically written onto a CMOS (Complementary Metal Oxide Semiconductor) programmable memory chip.

With best regards, 3T39. E-mail: snipped-for-privacy@hotmail.com

Hello, 3T39! You wrote to fixpc on Thu, 2 Mar 2006 13:24:21 -0000:

f>> is CMOS = BIOS in motherboard?

f>> TIA

T> Yes, the BIOS (Basic Input Output System) is the first level operating T> system which is typically written onto a CMOS (Complementary Metal Oxide T> Semiconductor) programmable memory chip.

To make that a little clearer, I should have said that the BIOS is the program, and the CMOS is the memory chip its kept on. Any reference to BIOS or CMOS with regard to Motherboards is in most cases the same thing. Hope this is helpful.

With best regards, 3T39. E-mail: snipped-for-privacy@hotmail.com

No.

Well, yes and no. You are correct to say that CMOS is not technically synonymous with BIOS, but in reference to computer setups the two terms are often interchanged.

On Thu, 2 Mar 2006 20:45:14 +0800, "fixpc" put finger to keyboard and composed:

No. Modern motherboards contain BIOS code in a flash EEPROM. The realtime clock (RTC) and CMOS RAM are located in a different chip, or are built into the chipset. CMOS RAM consists of 128 or 256 bytes which store info such as date and time, chipset register settings, hard drive geometry, etc. The flash EEPROM stores the compressed BIOS code and the ESCD table. The latter contains device specific settings such as lists of allowable IRQ, DMA, and IO addresses for PnP devices. After exiting BIOS setup, you may see an "updating NVRAM" message during the POST. This usually indicates that the ESCD table within the EEPROM is being updated. The same message does not appear after changing memory timings, for example, because these are determined by chipset register settings which are written to CMOS RAM.

- Franc Zabkar

BIOS = software (firmware) for motherboard

CMOS = hardware (memory of specific type)

Windows = Intel in computer (no)

The BIOS is the bootstrap program store in either an EPROM or flash memory. This code is used to allow the CPU to talk to the floppy and hard drives, as well as all the basic I/O ports.

The "CMOS" is a couple dozen bytes of Nonvolatile RAM in the Real Time Clock. It may be a separate IC, or part of the chipset used on the motherboard. These bytes are used to store some basic configuration data that is needed at bootup.