> From: "R.A. Cantrell" <[EMAIL PROTECTED]>
> Reply-To: <[EMAIL PROTECTED]> (iMac List)
> Date: Wed, 18 Sep 2002 11:19:15 -0500
> To: <[EMAIL PROTECTED]> (iMac List)
> Subject: Re: imac black screen and firmware update
>
> on 9/18/02 10:58 AM, Daniel Bouman at [EMAIL PROTECTED] wrote:
>
>> How can you install X then? When I purchased my iMac second hand it had
>> never been updated. When I tried to install X it just wouldn't allow it
>> until I ran the firmware update.
> Can you do a low level format, zero data scrub on the HD in an iMac and
> then install X, or does the low level format and zero data remove the
> "firmware update" that makes X not kill the Rom or Pram or whatever it
> kills if you don't do the firmware update? I repeat, What is Firmware?
Firmware, as it's name would imply, is halfway between hardware and
software. Many things besides computers have firmware, and it is not stored
on the hard drive.
My router has firmware, which can be updated over an ethernet connection.
My digital camera has firmware, which can be updated over a serial
connection. My CD burner has firmware, that can be updated over USB.
Basically, the word firmware is used instead of software for instructions
that are stored on a re-writeable chip inside a device, and tell it what to
do.
Before firmware, these instructions were permanently coded into ROM chips on
your computers motherboard. Firmware is stored in chips too, but they are
special chips, re-programable ROM chips, whose code can be updated.
Firmware allows the computer or peripheral developers to fix bugs or add
features to the very basic hardware level code of your computer or other
device, without requiring you to send your whole computer back in to have
the ROM chips replaced.
In a Mac, the firmware handles much of the things that the Mac does during
start up, before it even sees the hard drive. For instance, the code that
tells the computer how and where to look for the hard drive, how to
initialize the USB and firewire ports for possible booting from devices
connected to them, how to start loading the operating system from disk, and
etc. may be handled by firmware.
To upgrade my iMacs firmware, I had to download a program from Apple, run
it, and at a certain point in the program it said something like "please
depress the programmer's switch on the side of your computer, click okay to
restart the computer, and continue to hold it (the programmer's switch) in
until you hear three beeps. A little weird and scary, like giving your
computer a brain transplant at the most basic level.
Hope this clears it up a little, I didn't go into much detail, because most
people don't need to know the details of how it works, and because I don't
know the details. =o)
-John
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