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Flash memory in motherboards?

Discussion in 'Electronic Design' started by [email protected], Jun 8, 2006.

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  1. Guest

    So... when can we expect motherboards to use Flash memory (instead of
    battery-powered NVRAM) to store BIOS settings for our motherboards?

    Those coin lithium batteries are... old-fashioned.

    Even the newer Asus boards seem to have a lithium battery for storing
    BIOS settings...

    (press Don't Install if it asks to update your Macromedia.)

  2. That would be a waste of money (something MB manufactuers are loathe
    to do). The battery is needed anyway for the RTC. Keeping an
    additional chunk of RAM alive is virtually free. What do you suggest,
    an expensive double-layer capacitor? Flash would also be less
    approprate than EEPROM technology.

    Best regards,
    Spehro Pefhany
  3. Guest

    I thought EEPROM was more expensive than Flash. Oh well... my
    information must be out of date.

    Thanks for the reminder re: the RTC...
  4. Not out of date. It *is* cheaper for *large* memory sizes, but...

    1] In your reference above, see the "sector erase" issue with flash.
    EEPROM can be changed one byte at a time.

    2] The amount of memory required for BIOS *settings* (as opposed to
    the BIOS *program*) is quite small. Early ones were 64 bytes with the
    first 16 used for the RTC. Newer ones are probably several times that
    size, but still tiny compared to even a small flash memory. The
    smallest flash memory out of the 2200+ different types that Digikey
    carries is 256K bits (there's one shown erroneously as 1K, but it's
    actually 1M). They go up to a rather staggering 8G bits. EEPROMs,
    OTOH, start at 128 bits (16 bytes) and go up to about 1M bits. So, not
    only do you have the sector erase issue, but most of the memory would
    be wasted.

    Of course some settings *are* stored in flash, in a sense, since the
    factory default settings are part of the BIOS program, which is
    generally stored in flash these days. One could write a BIOS to store
    the settings in the large program flash, if it has the ability to
    boostrap, but that could result in a dead motherboard and an angry
    customer if the power failed or a crash occured during the routine
    writing of values, so I think most engineers will not be overly eager
    to invite that kind of problem to the door. Even if it happens only
    rarely, it's an extremely serious problem to the user.

    Best regards,
    Spehro Pefhany
  5. Pooh Bear

    Pooh Bear Guest

    Not to mention that you would lose the 'discharge CMOS' option with a jumper !
    An invaluable aid.

  6. One could argue that even the RTC is almost not needed in most desktop
    PCs now, they could get the time direct off the Net. Then you do have
    some savings - no pesky battery, and no CMOS ram.


    Adrian Jansen adrianjansen at internode dot on dot net
    Design Engineer J & K Micro Systems
    Microcomputer solutions for industrial control
    Note reply address is invalid, convert address above to machine form.
  7. Pooh Bear

    Pooh Bear Guest

    You're assuming everyone's connected to the 'net' !

  8. I expect functionally PC-like thingies (perhaps thin clients on
    wireless mesh networks) may well go that way.

    Best regards,
    Spehro Pefhany
  9. Deefoo

    Deefoo Guest

    As if anyone cares about wasted memory in the PC world.

  10. I have not noticed any video cards which use 1G of memory where a mere
    64M would do.

    Best regards,
    Spehro Pefhany
  11. Deefoo

    Deefoo Guest

    And you think that all those 64M bytes are being used? Hardware guys put on
    enough memory so software guys have plenty to waste.

  12. Michael

    Michael Guest

    If you object to the coin cell, remove it and wire in a series pair of AA cells
    (assuming the coin is 3v, of course). The last time I did this mod was in 1999,
    to an IBM PC-AT. BIOS was still fine yesterday when I used that machine to
    assemble some MC68705 code.
  13. Michael

    Michael Guest

    Agreed. Heartily! That breed of assumption is too common, causes no end of
    Of the half dozen PC's I use, only one ever connects to the web.
  14. Keith

    Keith Guest

    64MB isn't much these days either. Even this laptop has 128MB.
  15. Guest

    I might just do something along those lines.

    My NEC 486 laptop's lithium battery's shot, and the battery in my
    Pentium II-366 MHz laptop is starting to go on the fritz...

    On a positive note, though, I finally got my PII laptop to
    remote-control my main desktop machine last night (using vnc... that
    Microsoft Remote Desktop Connection didn't work for me)

    - Another Michael ;-)
  16. Tim Auton

    Tim Auton Guest

    If you're running Mac OS X or Windows Vista then you probably are
    using a good chunk of it.

  17. Guest

    Say it isn't so! When you run Unreal Tournament 2004 or Quake 4, that
    GB of video ram can come in handy!
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