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.In the old days, each program claimed a fixed amount of RAM for itself as soon as you launched it.You could see this number or even change it in the program's Get Info box.When you launched aprogram, it instantly claimed 20 MB of memory (or whatever its programmers thought it mightneed).But in Mac OS X, memory allotments are dynamic (changing).When you launch a program, it mightnot use very much RAM at all.But when you then use that program to open a huge, complexdocument, the system supplies more memory automatically.Then, when you close that document,Mac OS X automatically returns the RAM it was using to the "pot," so that it's available for use byother programs and functions.It's true that the About This Mac command no longer opens a little graph depicting how much RAMeach program is using.There's no longer much point.The answer is always, "exactly as much as itneeds, and it's changing minute by minute."Still, if you're desperate to know how much memory each of your running programs is using at thisinstant, open your Applications Utilities folder.Open the program called Process Viewer.Itpresents a little table showing what percentage of your Mac's memory each running program is using(see Section 9.2.24).Then there's the matter of virtual memory, which is a computer scheme that helps you open moreprograms simultaneously than should fit into the amount of RAM (electronic memory) your computerhas.It works by using a chunk of hard drive space as temporary overflow RAM when necessary.Ofcourse, real memory delivers information to your Mac's brain about 100 times faster than the harddrive, which is why virtual memory gained a reputation in the old Mac OS for slowing down yourmachine.In Mac OS X, virtual memory is turned on all the time.But these days, virtual memory is far less likely to slow down your machine for a couple reasons: First, because each program uses only asmuch RAM as it needs to begin with, so far less is wasted; second, because virtual memory puts onlypieces of your programs onto the hard drive.In any case, even if you have 50 programs open, MacOS X devotes your Mac's actual RAM to whatever program is frontmost, so the active programdoesn't grow sluggish.You'll notice the sluggishness kicking in only when switching programs orwhen working on an absolutely huge document that overwhelms your installed RAM.(Want to seehow much virtual memory has kicked in? Mac OS X can show you.See Secrets of Virtual Memory forinstructions.)Therefore, if you find yourself receiving "out of memory" messages, which are otherwise unheard ofin Mac OS X, it's probably because your hard drive is running out of space, thereby thwarting theefforts of Mac OS X's virtual memory scheme.Make more room or install more RAM.This Application menu (Figure 4-1) offers a number of commands pertaining to the entire program and itswindows, including About, Quit, and Hide.4.1.2 Quitting ProgramsYou quit a program in Mac OS X by pressing -Q, which is the keyboard equivalent of choosing the Quitcommand.For Macintosh and Windows veterans, the only tricky part here is that the Quit command is no longerin the File menu it's now at the bottom of the Application menu.But Mac OS X offers two much more fun ways to quit a program:Control-click a program's Dock icon and choose Quit from the pop-up menu.When you've highlighted a Dock icon by pressing -Tab to rotate through the running programs, typethe letter Q without releasing the key.The program quits instantly.Figure 4-1.The first menu in every program lets you know, at a glance, which program you'reactually in.One of the biggest changes veteran Mac users have to make in adopting Mac OS X isgetting used to the fact that this new menu contains commands that, in Mac OS 9, were scatteredamong the File, , and right-side Application menus. 4.1.3 Force Quitting ProgramsEverybody knows that Mac OS X is a rock-solid operating system, but that doesn't mean that programs neverscrew up.Individual programs are as likely as ever to freeze or lock up.In such cases, you have no choice but toforce quit the program to terminate it with a blunt instrument.The big Mac OS X difference is that doing so doesn't destabilize your Mac, meaning you don't have to restart it.In fact, you can usually reopen the very same program and get on with your life.You can force quit a stuck program in any of several ways.First, you can Control-click its Dock icon (or just holdyour mouse down on it).Once the pop-up menu appears, press Option so that the Quit command now says ForceQuit (see Figure 4-2).Bingo that program is outta here.Second, you can press Option- -Esc, the traditional Mac force quit keystroke.Third, you can chooseForce Quit.Either way, proceed as shown in Figure 4-2.Again, force quitting is no longer bad for your Mac.Dire warnings no longer appear.The only downside to forcequitting a program is that you lose any unsaved changes to your open documents.Figure 4-2.Top: You can force quit a program from the Dock thanks to the Option key.Bottom: Whenyou press Option- -Esc or choose Force Quit from the menu, a tidy box listing all open programsappears
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