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is CMOS = BIOS in motherboard?

Discussion in 'Electronic Repair' started by fixpc, Mar 2, 2006.

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  1. fixpc

    fixpc Guest

    is CMOS = BIOS in motherboard?

  2. 3T39

    3T39 Guest

    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:
  3. 3T39

    3T39 Guest

    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:
  4. Damir

    Damir Guest

  5. Farmer Giles

    Farmer Giles Guest

    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.
  6. Mike Berger

    Mike Berger Guest

    No. The BIOS is a collection of subroutines for communicating with
    your hardware. Parameters and settings for the BIOS are usually kept
    in CMOS memory, but the BIOS itself is usually in a EAROM.
  7. Franc Zabkar

    Franc Zabkar Guest

    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
  8. gb

    gb Guest

    BIOS = software (firmware) for motherboard

    CMOS = hardware (memory of specific type)

    Windows = Intel in computer (no)

  9. 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.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
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