CertiGuide to A+ (A+ 4 Real)  9  Chapter 7: History, Installing and Use of the MacOS       9  You are Booted Up, Now What?

Virtual Memory 1 Connecting to a Network

The creation of the kernels in UNIX has steadily kept up with the very fast-paced development of hardware technology. Of course, I also mean the support for multiple processors. Here is where Mac OS X introduces a new technology to provide continued support for two microprocessors, with symmetric multiprocessing or SMP. Preceding versions of the Mac OS only offered limited support for such multiprocessing, and were not too useful, except when such support could sound good in a commercial. But Mac OS X offers true, full multiprocessing with SMP. By simple definition, SMP is the ability to use fully two or more processors simultaneously. SMP is really a very complicated setup where the operating system itself is designed to keep both the microprocessors working in a well-organized manner. This is how Mac OS X can very effectively distribute tasks between processors to aid system-wide operation.

Do not confuse this with pre-emptive multitasking, where the OS distributes tasks out among the programs themselves, not the processors. This type of collaboration allows for an atmosphere in which we can both multiply system and program functionality. Developers at Apple have toyed with multiprocessor support in the past, but until now have not been able to make the OS able to use more than one processor. It is also worth mentioning that while symmetric multiprocessing enables the Mac to do more, and faster, it cannot exceed the limits placed on your computer by the existing hardware (i.e. your hard drive or graphics card).

It is also useful to point out that with Mac OS X, software developers do not have to write code for multiprocessor support; Mac OS X will take care of implementation. Programs that have multithreading support will run even better.

If you are interested in seeing all of these tools working together, perform the following test in Mac OS X:

• Download software from the net
  
  
• Print from AppleWorks
  
  
• Play some mp3s with iTunes
  
  
• Search for movie times or flight info with Sherlock
  
  
• Chat with Yahoo IM
  
  
• Invite people to an iCal event

Now pull down a menu and see if performance of any of the above named tasks is affected. Now try this little test in Mac OS 8.6 or 9 and see just how long it takes everything to stop. See what I mean?

Now that we’ve covered the key differences in Mac OS X and earlier versions, with regard to multitasking and virtual memory, you can see just one of the reasons I crossed over to the Mac OS X side. As you can see, not only is Mac OS X superior to it’s predecessors, it’s in many ways far superior to many other operating systems on the market today.

One word about Protected Memory- Mac OS X has a feature called protected memory. This means that each application the Mac runs gets its own separated memory. This memory is protected in the sense that if there is a problem or if the application crashes, it will shut down and that particular memory will be closed. This will prevent it from affecting any other processes or their protected memory, as well as the operating system itself.

Virtual Memory 1 Connecting to a Network