On 21 Sep 99, at 15:05, Sami Garzon wrote:

> Hi all. I hope I'm not boring you all with my simple questions. I
> just want to know a little more about updating BIOS. How is this
> process? How can a BIOS be updated? Any BIOS can be updated?

> From what I understand, only EPROM BIOSes can be updated, because
> the others are uneraseable. Don't know if this is true, please
> correct me. And what is 'flashing' a BIOS? Is this related with
> updating?

  There are two basic sorts of EPROMs:

1. UV-EPROM
  The old contents of the ROM are erased by uncovering a "window" and
shining a bright ultraviolet light onto the chip surface.

2. EEPROM
  The old contents of the ROM are erased by supplying a relatively-
large (in chip terms) electric current through the chip.

  In either case, a new set of contents can then be recorded into the
chip using an "EPROM Programmer" device.

  Hmmm...  I have no ultraviolet light, and no EPROM programmer on
hand.  When I've updated a BIOS on EPROM, it has been by exchanging
my old chip for a fresh one from the motherboard manufacturer.


  As a storage medium for BIOSes, EPROMs have been giving way to
"flash memory" devices.  These resemble ROM, in that they keep their
contents when there is no power, but resemble RAM in that they can be
rewritten using electrical current which is fairly close to normal
operating levels for chips.  So it's relatively easy to include
circuitry on a motherboard that lets software rewrite this kind of
memory.  No UV light; no EPROM programmer; just a few gates and
jumpers.
  "Flashing" a BIOS is rewriting the flash memory where the BIOS is
stored.

  [RAM is totally changable.  The process of erasing EPROMs is
stressful, and can only be done a couple of hundred times before the
chip begins to fail.  Flash memory can be rewritten thousands or tens
of thousands of times.
  Flash memory is also available on PCMCIA cards, providing a compact
but expensive form of removable storage for digital cameras, handheld
devices (PDAs), and network equipment.]

                  Visit our website regularly for FAQs,
               articles, how-to's, tech tips and much more
                  http://nospin.com - http://nospin.org