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Tweak List: Kernel

kernel - n - the central part of anything ; the nucleus; the core (def. 5, Webster's Encyclopedic Unabridged Dictionary of the English Language)

The idea of a kernel may seem very foreign to Mac users. Here's how the current MacOS works:

The MacOS is really a big fat piece of software which provides access to the Mac APIs, and also provides the basic services which the APIs require to function. The system software runs directly on top of the hardware on which it is running. The system software is not only responsible for properly responding to system calls, but also for hardware tasks such as memory management, I/O functions, drivers, video, and others.

That's a lot of work to demand from a single piece of software!

A kernel makes the architecture of an operating system much more streamlined.

With a kernel-based system, the "operating system" is divided into two parts:

• the kernel, which loads up first, and is responsible for providing basic hardware-related services, such as I/O, memory management, and others. The kernel is fine tuned to run on the hardware it is designed to keep working
• everything else - on top of the kernel, any software layer can be applied

Only the kernel need be hardware-specific, which makes the portability of the entire operating system a lot easier than if it has been one mass of code.

The kernel has its roots in such operating systems as UNIX, and more recently MacOS X (Server). Microsoft has also adopted a kernel-based approach for Windows NT, and most likely for Windows 2000.

There are many types of kernels, and each have their advantages and disadvantages. More soon…