System Software

System software deals with the physical complexities of how the hardware works.

System software generally consists of four kinds of programs: Bootstrap loader Diagnostic routines Basic input / output system Operating system

Four Kinds of Programs1. Bootstrap loader

It is a program that is stored permanently in the computer’s electronic circuitry.

When you turn on your computer, the bootstrap loader obtains the operating system from your hard disk (or floppy disk) and loads it into memory.

This is commonly called booting the system.2. Diagnostic routines

They are also programs stored in the computer’s electronic circuitry.

They startup when you turn on the machine. They test the primary storage, the central

processing unit (CPU), and other parts of the system.

Their purpose is to make sure the computer is running properly.

Four Kinds of Programs3. Basic Input – Output System

(BIOS) It consists of service programs stored in

primary storage. These programs enable to interpret

keyboard characters and transmit characters to the monitor or to a flash drive.

4. Operating System The operating system is a collection of

programs that helps the computer manage its resources.

It enables the users to run programs. It manages memory, data and files.

General Characteristics of an Operating System Utility programs.

These programs perform common repetitious tasks or “housekeeping tasks”.

One important utility program is used for formatting blank flash drive.

With a formatted disk, you can use a utility program to copy or duplicate files or programs from another disk.

You can erase or delete old files from a disk.

You can rename the files on a disk – that is, give them new file names.

General Characteristics of an Operating System …

Every computer has an operating system.

Larger computer systems like mainframe and minicomputers have very sophisticated ones.

A popular operating system for Digital Equipment Corporation (DEC) minicomputers is VAX/VMS.

These operating systems have very powerful capabilities, including virtual memory, multiprogramming, and multiprocessing, multitasking

General Characteristics of an Operating System …

Virtual Memory An operating system with virtual memory

increases the amount of memory available to run programs.

Without virtual memory, an entire program must be read into the computer system’s memory before it can run.

Therefore, the size of the memory determines the largest programs that can be run.

With virtual memory, the operating system divides large programs into parts and stores these parts on a secondary storage, usually a disk.

Each part is then read into the computer system’s memory only when it is needed.

This allows a computer system to run very large programs.

General Characteristics of an Operating System …

Multiprogramming and Multiprocessing

For multiprogramming, the operating system interrupts and switches rapidly back and forth between several programs while they are running.

This allows several different users to run different programs seemingly at the same time.

For multiprocessing, the operating system controls two or more central processing units.

DOSDOS stands for Disk Operating System.

Originally developed by Microsoft. It was the original standard operating system

for all microcomputers used to be called IBM-compatibles or DOS-based.

Advantages Widely used: Even today DOS is still used on

a significant percentage of all the microcomputers of the world.

Number of applications: An enormous number of application programs have been written for DOS than for any other operating system.

Runs on inexpensive hardware: DOS runs on many computers – old and new – that are reasonably priced.

DOS … Disadvantages

DOS is a software, and software can perform only for the hardware for which it was designed.

The first version of DOS was introduced in 1981 for microcomputers with floppy disk drives.

This first version did not support hard-disk drives.

Since that time, hardware has evolved significantly.

Fortunately the new versions of DOS were written so that older application programs could still work with them.

But, unfortunately, this also constrained DOS’s ability to fully use all the power of today’s microcomputers.

DOS … Disadvantages

Limited primary storage: Before application program can be used, it must be stored in the computer’s primary storage.

An application program running with DOS has direct access to only 640 kilobytes (about 640,000 characters) of primary storage.

With the newer versions of DOS, several additional kilobytes can be accessed.

However, almost all of the new spreadsheet, database management and graphics programs require more main memory.

Single Tasking only: Multitasking is the term given to operating systems that allow a single user to run several different application programs at the same time.

MS-DOS can only support one user and one program at the same time.

Microsoft Windows Advantages

Multiprocessing: Multiprocessing is similar to multitasking except that the applications are run independently and at the same time.

For example, you could be printing a word processing document and using a database management program at the same time.

With multitasking, the speed at which the document is printed is affected by the demands of the database management program.

With multiprocessing, the demands of the database management program do not affect the printing of the document.

Flexibility: Windows does not require DOS and is able to run with a much wider variety of powerful computers and microprocessors.

Microsoft Windows … Advantages …

Internet Access: For an internet access and to connect to other computers, one must have to have TCP/IP and Internet utilities.

Both these utilities are built into Windows . Easy Upgrades: Installation of new hardware such

as a modem can be very complex and difficult. A new standard called Plug and Play has greatly

simplified the installation of new hardware problem. Disadvantages

Minimum system configuration: You need at least a 486 processor and a hard disk to operate this system.

Fewer Applications: Compared to DOS and old Windows, fewer applications have been written specifically for Windows .

Microsoft Windows Advantages

Performance: It is faster in many common tasks like starting up, loading applications, and shutting down.

It includes a tune up wizard to automatically monitor system operations and suggests ways to improve performance.

Internet integration: It is fully integrated with Internet Explorer, making internet access easier and faster.

A new standard called Plug and Play has greatly simplified the installation of new hardware problem.

Ease of use: Plug and play capability is extended to support the newest advances in technology.

Multiple views of an application or multiple applications can be viewed on separate monitors simultaneously.

Multimedia: It has advanced audio video capability.

Microsoft Windows … Disadvantages

Minimum system configuration: You need at least a Pentium processor, with larger hard disk and more main memory is required to operate this system.

Fewer Applications:

UNIX Advantages

Unix has the advantage of being a portable operating system.

That means that it is used with different types of computer systems.

It is used with microcomputers, minicomputers, mainframes and supercomputers.

The other systems are designed for microcomputers and are not nearly as portable.

Multitasking: Unix enables you to do multitasking. It allows you to run several programs at the same

time, each one sharing the CPU. Multiprocessing: Unix, like Windows 98 and XP,

enables you to run several programs independently and at the same time.

Networking: Unix is able to share files over electronic networks with several different kinds of equipment.

Unix has been successfully and reliably doing this for years.

UNIX … Disadvantages

Unix was a minicomputer operating system used by programmers and computer science professionals, some time before the rise of microcomputers.

This means it has certain qualities that make it useful for programmers.

But some of these features make Unix difficult for end users.

Limited business application software: This is a great barrier at the moment.

No Unix standard: They say that there more flavors of Unix that ice cream has.

Its commands are frequently long and complex. Unix is a powerful and complex operating system.

Unix is a popular operating system among researchers and educators. Some observers believe that it could yet become a leader among operating systems