> I'm a novice on macs. We all were, at one point :) > I have an old G4 17" powerbook. That could make it up to ten years old. The 17-inch PowerBook first appeared in 2003, and vanished three years later in 2006 when Apple shifted the base architecture from PowerPC to Intel x86. > I don't know the type of OS that l have on my mac. You would be running a version of Mac OS X of some kind. You can find out exactly what is currently installed (and a lot more info) with this procedure: - Go to the Apple menu, at the top left corner of the screen and choose the option "About this Mac" - This opens a simple 'about' box that will tell you: - you're running Mac OS X, with the version number displayed underneath, - the processor type and its speed, - how much physical memory is installed, and what type, and - the name of the startup, or boot, disk that the OS X install is running from. - Click the "More Info..." button to launch the "System Profiler" utility. System Profiler holds all the important hardware and software information you will need, so feel free to explore. There are two important pieces of information you should make note of, one is the Mac's serial number (every Mac knows its own number), the other is the "Model Identifier" which willl look something like "PowerBook5,3". If someone asks you what model of Mac you have, give them the Model ID as it will pinpoint your machine exactly out of all the similar-looking ones. Once you know your Model ID, visit this page: http://www.everymac.com/systems/by_capability/mac-specs-by-machine-model-machine-id.html and search for the Model ID string, then follow its link to find a concise and detailed configuration report for your PowerBook, including what expansion options are open to you. > How can upgrade the Os, I tried to download mountain lion OS but it >looks like > it's not compatible to my old system. No, it is not. The change from PowerPC to Intel processors was a radical one, and the last version of Mac OS X that can run on a PowerPC based machine such as yours is Mac OS X 10.5 'Leopard'. You can go no further because 10.6 and upwards require an Intel processor, and to get that you will need to replace the entire computer -- you can't change CPUs and hope to be able to run newer software. If you would like to learn more about the differences between Mac OS and Windows, do a Google search for "Apple Switch 101". Apple maintain a very good beginner's and switcher's tutorial and reference section that explains things in terms you will be familiar with, and it can all be done from inside a web browser. Welcome to the friendly face of personal computing :) Geoffrey -- -- -------------------- Endian Little Hate I ----------------------- -- What you think, you create. What you create, you become. What you become, you express. What you express, you experience. What you experience, you are. What you are, you think.