First, there are basically two parts to flashing your agenda:  

  o LOADING (transferring the file from your computer to the agenda's memory)
  o FLASHING (telling the agenda to put what you just loaded into memory down        onto the flash chip)

Now, with that in mind, I bring you the following points about why flashing
your kernel and romdisk is really quite safe.

1.  Even if a flash goes horribly, horribly wrong, your agenda can still
be easily restored to full working condition as long as you have the 'PMON'
prompt.

2.  The PMON area of the flash can be write-protected so that you can
*never* overwrite it accidentally, therefore assuring that point 1 is always
true.  This procedure is highly recommended for all users, and is documented
both in list archives and the vrflash documentation.

3.  So what happens if your agenda, your computer, or your flashing software
crashes during the LOADING phase?  Nothing.  It is completely harmless.  All
that has happened is you didn't completely load the appropriate file into
the agenda's memory.  But since ram is volatile and you haven't issued a
flash command yet, nothing has really happened to your agenda.  You could,
if you wanted, restart your agenda immediately after a failed LOAD phase and
it would be just as you left it.  Generally you can just retry the flash
immediately if your upgrade fails during the LOADING phase and all is well.
No need to fear this.

4.  But what happens if your flashing program (vrflash, minicom, etc) or
your computer crashes while FLASHING?  Again, probably nothing.  Your agenda
will probably still finish the flash as expected.  Why?  Because all the
terminal program is doing at the time of flash is issuing a single command
to the agenda that tells it what to flash where.  Once that command has been
accepted by PMON and is processing, it will continue to do so regardless of
whether or not your client computer or terminal software is online to watch
it.  99% of the time this won't even necessitate a reflash.  So you really
need not fear this either.  

5.  So what happens if your *agenda* dies while flashing?  In this case,
you'll probably have to reflash.  The reason is because the agenda more than
likely finished only X% of the flash, but not all of it.  This is kind of
like installing half a kernel or half of Windoze.  It won't work until your
agenda survives a complete flash.  But even still, if we review point 1, we
can rest easy knowing that soon we will have a working kernel and romdisk
again.  Simply replace your batteries and reflash.

So as you can see, the only two things to worry about are keeping your
agenda alive while flashing and write-protecting PMON so you never overwrite
it.  The first is easy to fix:  flash with fresh batteries.  The second is
just as easy and takes about 30 seconds after you read the docs.  If you
follow those two simple rules, you never need to sweat while flashing your
kernel or romdisk.  

Yes, flashing PMON is another animal altogether, and it shouldn't be
attempted by novices (or sane experts).  Should you ever choose to do it,
sweating, uncontrolled shiverring, and mild convulsing are to be expected.
But really, even when flashing PMON, you only need to be concerned with your
agenda dying in the middle of the flash.  A failed load, or your computer
dying after sending the flash command should still be safe for the reasons
outlined above.  So if you're going to upgrade PMON, be very, very sure your
batteries are good and that you know what you're doing.

Hope this helps,

Jeff

-- 
  Jeff Carneal - jeff@soldmy.net

  The opinions expressed above aren't really mine.
  They belong to someone else who also refuses to 
  take responsibility for them. 

