upgrade os x 3.9

I want to upgrade my os x 3.9 to at least os x 4. How do I go about this? Is it a purchase? How high can I upgrade without spending a lot on upgrading memory or any other necessary components that might be required.
Thank you.

You will have to buy the retail copy of tiger, you should be able to pick a set of disks off ebay for not too much (make sure they are retail copies, not grey copies that shipped with specific macs)

The other thing is RAM, I would recommend 1 gig of RAM or above for tiger, what mac model do you have?

Machine Model: iBook G4
CPU Type: PowerPC G4 (1.1)
Number Of CPUs: 1
CPU Speed: 1.2 GHz
L2 Cache (per CPU): 512 KB
Memory: 256 MB
Bus Speed: 133 MHz
Boot ROM Version: 4.8.7f1

that will run tiger very well, you just need to upgrade the memory

http://www.everymac.com/systems/apple/ibook/stats/ibook_g4_1.2_14.html


http://www.everymac.com/systems/apple/ibook/faq/ibook-type-of-memory-used-how-to-install-ram.html

A one gig Dimm will cost just over $40, maxing your mac out at 1.25 gig of ram

Thank you. I appreciate the help.

In looking to find Tiger, I found that it was labeled old version with Apple Mac OS X Version 10.5.1 Leopard indicated as a newer version. Would this be a better upgrade for my computer?

you could run Leopard or Tiger, its up to you, your mac can run either

HI, this is my com's detail

Machine Model: iBook G4
CPU Type: PowerPC G4 (1.1)
Number Of CPUs: 1
CPU Speed: 1.2 GHz
L2 Cache (per CPU): 512 KB
Memory: 768 MB
Bus Speed: 133 MHz
Boot ROM Version: 4.8.5f0

I think i am pretty similar to what "pdx1one" has it before..
little different for the last line ..

SO i am trying to follow instruction here too..is it ok? so should i get OS X 10.5.1 Leopard? and install it? that's all?..I have no idea how to do handle those stuff even though i have been mac user for nearly 10 years

Please help. I really think its time for me to do somthing about this..I can't even connect to my iphone...because my laptop is way too old..and i alwasy have newest mac at work..so i dont mind saving my laptop..

Thanks!