Page 26 - DCAP103_Principle of operating system

Unit 1: Operating System

generations of computer science students to study and comprehend the kernel. However, the Notes
advocates of monolithic kernels claim that in spite of their size such kernels are easier to design
correctly, and thus they can be improved more quickly than can microkernel-based systems.

Moreover, the size of the compiled kernel is only a tiny fraction of that of the source code,
for example roughly 1.1MB in the case of Linux version 2.4 on a typical Red Hat Linux 9
desktop installation. Contributing to the small size of the compiled Linux kernel is its ability to
dynamically load modules at runtime, so that the basic kernel contains only those components
that are necessary for the system to start itself and to load modules.
The monolithic Linux kernel can be made extremely small not only because of its ability to
dynamically load modules but also because of its ease of customization. In fact, there are some
versions that are small enough to fit together with a large number of utilities and other programs
on a single floppy disk and still provide a fully functional operating system (one of the most
popular of which is muLinux). This ability to miniaturize its kernel has also led to a rapid growth
in the use of Linux in embedded systems (i.e., computer circuitry built into other products).

Although microkernels are very small by themselves, in combination with all their required
auxiliary code they are, in fact, often larger than monolithic kernels. Advocates of monolithic
kernels also point out that the two-tiered structure of microkernel systems, in which most of
the operating system does not interact directly with the hardware, creates a not-insignificant
cost in terms of system efficiency.

File-system management is one of the most visible components of an
operating system.

Self Assessment

Fill in the blanks:

1. An .................... is a software program that manages the hardware and software resources
of a computer.

2. Operating systems can be explored from two viewpoints: the .................... and the system.
3. A .................... manages the execution of user programs.
4. A .................... is the mechanism used by an application program to request service from
the operating system.

1.7 Operating System Functions

1.7.1 What is an Operating System?

The operating system is the core software component of your computer. It performs many
functions and is, in very basic terms, an interface between your computer and the outside world.
In the section about hardware, a computer is described as consisting of several component parts
including your monitor, keyboard, mouse, and other parts. The operating system provides an
interface to these parts using what is referred to as “drivers”. This is why sometimes when
you install a new printer or other piece of hardware, your system will ask you to install more
software called a driver.

LOVELY PROFESSIONAL UNIVERSITY 19