infinite-loop said:
This is a 10-year old Mac...so I would be VERY wary about spending any money on it. It's only worth a couple of quid..if that.! It will not run any OS after OS 8. It sounds like the Ram Chips and/or the V-Ram chips have packed in. Possibly some Mother-Board components too..to be honest it's not even worth the cost of having it tested.
So according to you my Macintosh Quadra 650 (a machine OVER 10 years old and a 68K to boot) that's hosting my family homepage isn't worth spending money on. I beg to differ...
Before you try and replace anything drastic, it's possible that the PRAM battery has died. This will prevent some Macs from turning on at all (happened to my StarMax 4000 Mac clone). A simple replacement of this battery might solve your problems with this machine.
See here for some more information on the PRAM batteries in various Macs:
http://www.academ.com/info/macintosh/
In order to test to make sure it's just that PRAM battery, unplug the Mac and open it up (See
here for your particular Mac). Near the battery there should be a little button to press.
ONLY PRESS THIS BUTTON ONCE AND FOR ONE SECOND!! (Holding it for longer can damage the logic board). After doing that, close everything up, plug the Mac in, and hit the power button. Once you do this, the Mac should start up.
If the battery is dead, the minute you shut down your Mac it won't boot up again. As I mentioned, replacing this battery will bring everything back to life.
As for operating systems, you should be able to install up to Mac OS 9.1 on it. It's probably best to stick with 8.6 since 9.x might add more bloat and nothing that significant to warrant it's upgrade, but that's entirely up to you.
While you could upgrade it, you would probably be better served spending money on a new Mac, but if you have some extra old RAM (not EDO, has to be FPM DIMMs according to Apple) you can use that. Any old SCSI hard drive should work as well. Of course, since the 7200 has PCI slots you can install a mac compatible IDE controller and use an IDE drive in there. You can also install some USB cards in there in order to use a different mouse and keyboard other than the hard-to-find ADB peripherals.
Here's more information on the 7200:
http://lowendmac.com/ppc/7200.shtml
Good luck.