I’ve been wondering (backups)… which always gets me in trouble…

That's the Internet for you

Some of the files on a StreetPilot/Zümo/Nüvi are accessed in-situ - and prevent unit working, if they aren't there - for example, the *.VPM (voice files) and *.IMG (maps). (*.IMG are quite a special case, because, in general, you can't download these from anywhere).

Other files are copied into 'some other place', as a one-off and the unit will continue to run, if you subsequently delete them - for example, *.SWF (vehicle file), *.JPG (splash screen), *.UNL (map unlock codes).

Another group of files are the various firmware installers (*.BIN,*.GCD etc). The unit examines these at boot time and may execute them, so that their contents are transferred to the various components. The files themselves can then be safely deleted. The 'main' firmware and the bluetooth firmware can subsequently be downgraded, if required, but other components just check the version numbers and will not downgrade (eg the Sirf firmware).

(PS - a little inaccuracy, saves a lot of explanation )

Anecdotal "evidence" says backups can be restored -- I asked awhile back if we we kidding ourselves.

You can downgrade your firmware. Plenty of people have done so in the past. However, I'm thinking that what MIGHT have been said/meant was that the "GPS Software" cannot be downgraded -- I wouldn't know where you can find archived s/w versions of that.

Can I go back if I have all the original files?

You cannot do a true Factory Reset, but you might get close.

Backup up your maps is probably the best advice.

(...and since everything else is small in comparison, you may as well back them up as well!)

Hornbyp and bentbiker...

So I guess I'll do a b/u which I would have anyway because I have to try it myself to believe it... and didn't I read somewhere that size doesn't matter?

Going to see a Janice Joplin like performer, it ought to be fun.

Absolutely

Beware of some other strange goings-on, that might catch you out...

I mentioned earlier about the map unlock files (*.UNL). These contain the 25 digit unlock code, and they are only read once. Garmin have started deleting them before they ship the unit. On some units (eg StreetPilot C5xx), you can lose this information if you do a firmware downgrade. On the subsequent reboot, you'll get a "Can't Unlock Maps" message, if the .UNL file can't be re-read.
The Nüvi series seems much more resilient to this sort of problem, but earlier Nüvi 7xx's were doing it 'spontaneously'.

For this reason, I've been making it a habit to ensure this file exists. (same name as .IMG, but with .UNL extension - contains 25 digits from yellow voucher, or mygarmin.com ... or even GarminDevice.XML)

Backup & restore have been discussed in several topics. You may want to read this one:

http://www.poi-factory.com/node/9583

Well I did a test whit my Nuvi 350 , deleted all the files after making a back up on my PCs hard drive .the unit works whit no maps but is useless ,it's like a zombie . Copied all the files back on the unit and voila ,on the road again .So if any of you want to make a back up ,,, good advice and in case of mistake you can always go back .

You're a lot braver than I was!!!

I did, I found it quite informative...

Again thanks Gary..

Some Nuvi users have suddendly got a Directory Corrupt error when starting the GPS. Resolution (that does not involve sending your unit back to Garmin) is to format the Nuvi when it is plugged into the computer and then restore your backup. All fixed.

Some Nuvi users have suddendly got a Directory Corrupt error when starting the GPS. Resolution (that does not involve sending your unit back to Garmin) is to format the Nuvi when it is plugged into the computer and then restore your backup. All fixed.

Gary... Gary - there's an echo (echo) in here.