OS Components
In the previous section, you had a great opportunity to review the similarities and differences between Microsoft Windows, Mac OS X, and Linux. In this section, we start really exploring the internals of Microsoft Windows. Most of the exam covers Microsoft Windows as it is by far the largest install base and is most likely the OS you will work on frequently in your next job as a computer support technician or network administrator.
This section provides us an opportunity to review the components that provide the core services of the OS to run. In later sections, we look at more of the “front end” pieces of the operating system – such as Windows Explorer, My Computer, the Control Panel, and the command prompt. This section provides detail on the innards of the OS and how it all works together.
Core Services
Microsoft Windows is a very complex operating system with millions of lines of code. It has to be – just think of all of the different types of computers and components out there Microsoft has to support. With millions of different combinations of motherboards, hard drives, accessories, and software applications, Microsoft has a tremendous job to produce a stable OS which doesn’t crash at a moment’s notice.
I could insert a joke here about Windows crashing, but just think about the stability of your computer systems over the past few years. I very infrequently have my laptop suffer a crash – in fact, I can’t remember the last one I had.
The core services in Microsoft Windows are the file system, virtual memory, and the registry.
File System
The File System is responsible for managing all of the storage system activities. Windows NT based Operating Systems such as Windows 2000, XP, and Vista have two primary file systems available: FAT and NTFS. The Installable File System (IFS) Manager in the I/O Manager is responsible for managing file systems.
On FAT systems, it has two partition types available for each hard drive: primary and extended. A primary drive partition is what is commonly referred to as the “C:” drive. Up to 23 logical drives can exist in the extended partition – allowing you to partition one physical drive into several “drives” on your computer – e.g. C:, E:, F:, etc.
The active partition is the logical drive the system will boot up to. The system files need to be located on this partition and it must be set to active for the system to properly boot. The active partition must be the primary partition in a FAT system.
NTFS differs in many ways from FAT. NTFS can have up to four primary partitions or three primary partitions and one extended partition. Primary partitions can be marked as active in NTFS system.
One hard drive only supports up to 32 primary partitions plus logical drives.
Virtual Memory
PCs are often limited by the amount of physical RAM (Random Access Memory) they contain. Often, Windows requires more memory than the system physically has to open all of the applications and services you want to run. The Operating System exceeds the physical limits of the system by providing virtual memory, or memory space which is swapped back and forth to your physical hard disk. Later, you will learn about the paging file and how this swap occurs from physical memory to the hard disk.
Figure 27: Windows Task Manager
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