Hold down the C key while booting to boot from the installer disc. You have to be booted to the installer disc to installer the system. Software Update will not upgrade your system, only update it.
Software update, upgrade--what's the difference? - http://support.apple.com/kb/HT1444
Mac OS X 10.4, 10.5: About installation options - http://support.apple.com/kb/HT1545
Make sure the installer disc is a black retail version. Many people sell grey discs which only work in the Macs with which they were originally supplied.
Well I have tried both of these options and neither worked. I was unable to get access to the Pram and Pressing the C key didnt work either
according to http://support.apple.com/kb/ht1379 my inability to access the Pram is due to my logic board battery being knackered??? not sure if thats the case.
I have no idea how to access the firmware settings as te system preferences dont have any immeadiate clues.
Anyone have any more ideas or is this Mac for the scrap?
What version of Tiger 10.4 are you attempting to use?
If it is a gray-label, it likely won't work, as those are specific
to a computer model originally intended; a restore-install disc.
Usually these have identifiers on them for their intended Mac.
What numbers are on the Tiger disc? What Mac is it for?
The clock battery or PRAM battery should be replaced every
few years as they do not charge up. They are one-way. This
powers the parameter random access memory chip, where
settings for system function are stored.
The computer could use retail install DVD Leopard OS X 10.5.
This would be the best way to upgrade the OS X, unless you
happen to have a workable way to install OS 9.2.2 to use it
as Classic, to run older applications under Tiger OS X 10.4.11.
Good luck & happy computing!
Doesn't show the disc or doesn't show the disk (disk = hard drive, disc = optical drive so there is a huge difference in spelling and meaning). If it isn't showing the boot DVD it could be you have a bad optical drive, which I suppose could be related to corrupt PRAM from a bad battery, or it could just be mechanically bad.