System software is a set if one or more programs, designed to control the operation of a computer system. These programs do not solve specific problems like custom made application software. They are general program written to assist human in the use of the computer system by performing tasks, such as controlling all of the operation, required ton move data onto and out of a computer and all the steps in executing an application program. in general, system packages support the running of other software; communicate with peripheral devices (keyboard, mouse, CRT, printer, disk and tape devices, etc.); support the development of other types of software; and monitor the use if various hardware resources (memory, peripherals, CPU, etc.). Thus systems software makes the operation of the computer system more effective and efficient. The program included in systems software are called systems programs and the person who prepares systems software is referred as to as systems programmer.
Systems packages offer several advantages and conveniences to application programs and computer uses in general. Good systems software allows application packages to be run on the computer with less time and efforts. Without systems software, applications packages could no be run on the computer system. However, the production of systems software is a complex task that requires extensive knowledge and considerable specialized training in computer science. System programs, who prepare systems software, are highly trained computer specialists and important member of the computer architectural team. Because of its technical complexity, system software is rarely devolved in-house. They are normally developed and distributed by the computer manufactures. The customer who buy or leases a computer system would usually receive in addition to the hardware, some software needed to the effective operation of his computer. The system software is an essential part of a total computer system. its function is to compensate for the differences that exist between the use needs and the capabilities of the hardware. A computer without some kind of systems software would be very ineffective and most likely impossible to operate.
Categories/Types of System Software:
a. Operating System (OS):
b. Device Driver:
c. Utility Programs:
a. Operating Systems (OS):
Operating System (OS) is a collection of control, processing, and data management programs specially designed to manage the resources of the computer system and to facilitate the creation of programs and control their executions. OS is series of programs that monitor and control the overall operations of a computer.
OS may also be defined as the Resource Manager and the primary resource it manages, is the computer hardware. Modem computer systems are so complex and fast that they need internal control instead of human control. The complexity of system demands that jobs are controlled in that they are allowed to do for the sake of security, although overall the user is provided with greater flexibility.
The leading operating systems for PC are as follow:
Dos was the most popular operating system for 16-bit PCs. It is used today with older PCs based on the IBM PC standard because so much available application software was written for system using DOS. (PC-DOS is used executively with other 16-bit PCs. MS-DOS, developed by Microsoft, is used with other 160bit PCs that function like the IBM PC, IBM Compatibles.). DOS it self does not support multitasking and limits that size of a program in memory to 640K.
DOS is command-driven (text base), but it can present a graphical user interfaces by using Microsoft Windows (Version window 3.0, 3.1, 3.11 for workshop), a highly popular graphical user interfaces shell that runs in the conjunction with the DOS operating system.
Window supports limited forms of multitasking and networking but shares the memory limitations of DOS. Early versions of windows had some problems with application crashes when multiple programs competed for the same memory space.
Microsoft's Windows 98 and windows 95 are genuine 32-bit operating system. A 32-bit operating system can run faster than DOS, which could only address data in 32-bit chunks. Both Windows 98 and 95 provide a streamlined graphical user interface that arranges icons to provided instant access to common tasks. They can support software written for DOS but can also run programs that take up more than 640K of memory. Window 98 and 95 feature multitasking, multithreading (the ability to manage multiple independent tasks simultaneously), and powerful networking capabilities, including the capability to integrate fax, e-mail, and scheduling programs.
Window 98 is faster and more integrated with the Internet than Window 95, with support for new hardware technologies such as MMX, digital video disks (DVD), videoconferencing cameras, scanners, TV tuner-adapter cards, and joysticks. It provides capabilities for optimizing hardware performance and file management on the hard disk and enhanced three-dimensional graphics. The most visible feature of Window 98 is the integration of the operating system with web browser software. User will be able to work with the traditional Windows interface or use the web browser interface to display information. The user's hard disk can be viewed as an extension of the world wide web so that a document residing on the hard disk or on the web can be assessed the same way. Small applet programs (Java) on the window desktop can automatically retrieve information from specific web sites whenever the user logs onto the Internet. These applets can atomically update the desktop with the latest news, stock quotes, or weather.
Windows NT (for new technology) is another 32-bit operating system developed by Microsoft with features that make it appropriate for applications in large networked organizations. It is used as an operating system for high-performance workstations and network servers. Windows NT shares the same graphical user interface as the other Windows operating systems, but it has more powerful networking, multitasking, and memory-management capabilities. Window NT can support existing software written for DOS and Windows, and it can provide mainframe-like computing power for new applications with massive memory and file requirements. It can even support multiprocessing with multiple CPUs.
There are two versions of Windows NT; a Workstation version for user of standalone or client desktop computers. And a Server version designed to run on network servers. Windows NT Server includes tools for creating and operating websites. Unlike OS/2, windows NT is not tied to computer hardware based on Intel microprocessors.
Window CE has some of the capabilities of Windows, including its graphical user interface, but it designed to run on small handheld computers, personal digital assistants, or wireless communication devices such as pagers and cellular phones. It is a portable and compact operating system requiring very little memory. Non-PC and consumer devices can use this operating system to share information with Window-based PCs and connect to the Internet.
OS/2 is the 32-bit operating system for the powerful IBM or IBM-compatible PCs with Intel microprocessors. OS/2 is used for complex, memory-intensive applications or those that require networking, multitasking or large programs. OS/2 provides powerful desktop computer with mainframe-operating-system capabilities, such as multitasking and supporting multiple users in network, and it supports networked multimedia and pen computing applications.
OS/2 supports application that run under window and DOS and has its own graphical interface. There are now two versions of OS/2. OS/2 Warp is for personal use. It can accept voice-input commands and run Java applications without a web browser. OS.2 Warp Server has capabilities similar to windows NT for supporting networking, systems management, and Internet access.
UNIX is an interactive, multi-user, multitasking operating systems developed by Bell Laboratories in 1969 to help scientific researchers share data. Many people can use UNIX simultaneously to perform the same kind of tasks, or one user can run many tasks on UNIX concurrently. UNIX was developed to connect various machines together and is highly supportive of communications and networking. UNIX was designed for mini-computers but has various for PCs, workstations, and mainframes. It is often used on workstations and server computers. UNIX can run on many different kinds of computers and can be easily customized. Applications programs that run under UNIX can be ported from one computer to run on a different computer with little modification. UNIX also can store and manage a large number of files.
UNIX is considered powerful but very complex, with a legion of commands. Graphical user interfaces have been developed for UNIX. UNIX cannot respond well to problems caused by the overuse of system resources such as jobs or disk spaces.
If Operating System Ran Airlines
||Everybody pushes the airplane until it glides, then jumps on and lets the plane coast until it hits the ground again, then push again, jumps on again and so on.
||All the stewards, stewardesses, captains, baggage handlers and tickets agents look the same, act the same and talk the same. Every time you ask questions about details, you are told you don't need to know, don't want to know, and everything will be done for you without you having to know, so just shut up.
||To board the plane, you have your ticket stamped 10 different times by standing in 10 different lines. Then you fill out a form showing where you want to sit and whether it should look and feel like an ocean liner, a passenger train, or a bus. If you succeed in getting on board the plane and the plane succeeds in getting off the ground, you have a wonderful trip... except times when the rudder and flaps get frozen in position, in which case you have time to save your prayers and get yourself prepared before the crash.
||The airport terminal is nice and colorful, with friendly stewards and stewardesses easy access to the plane, and an uneventful takeoff... then the plane blows up without warning whatsoever.
||Everyone marshes out on the runway, says the password in unison and forms the outlines of the plane. Then they all set down and make a whooshing sound like they're flying.
||Everyone brings one piece of the plane with them when they come to the airport. They all get out on the runway and put the plane together piece by piece, arguing constantly about what kind of plane they are building.
UNIX also generates some security problems, because multiple jobs and users can access the same file simultaneously. Vendors have devolved different versions of UNIX that are in-compatible, thereby limiting software portability.
Mac Operating System (OS):
Mac Operating System (OS), the operating system for the Macintosh computer, futures multitasking as well as powerful multimedia and networking capabilities, and a mouse-driven graphical user interface. New features of this operating systems allow users to connect to, explore, and publish on the Internet and World Wide Web and to use Java software.
Functions of Operating System (OS):
Helps in booting up process of the computer
Checking that the hardware is functioning properly
Scheduling and loading of jobs in order to provide continuous processing
Control of user selection and operation of I/O devices and file handling
Calling into main storage of programs and subroutines, as and when required
Opening and closing files, checking of files labels etc.
Maintenance of directories in external storages
Passing of control from one program to another when more than one application programs occupy main storage
Provision of error corrections routines
Communications with the computer user by means of Input and output devices
Managing tasks such as multitasking, multiprogramming, multiprocessing, and timesharing
Major Components of Operating System (OS):
Most Operating System (OS) have many similar elements. These generally include:
At the heart of every OS is a program called supervisor. The overall coordination and the management of OS are performed by this program. Located in primary memory when the computer system is on, the supervisor initiates the call to other parts of the OS for resources and places any programs that are retrieved during the process into main memory.
Command Language Translator:
The command language translator transforms the needs of users onto actions that the OS takes. Like other software packages, the OS has its own language with which users and programmers issue commands. Commend language translator converts the English like commands of OS (DIR, COPY, CLS, or DEL) into the machine language of the computer.
I/O Control System (IOCS):
This input/output control system (IOCS )interacts with input and output hardware devices. Thus, if the supervisor determines that a program should be retrieved from hard disk to main memory for a user, it hands the task over to the IOCS. Supervisor actually supervise the input and output devices, the actual work is basically done by IOCS.
Computer hard disk is basically a library. The librarian is the software element that catalogs and manages data, file, directories, programs, space, and users.
Characteristics of OS (Operating System):
The stand alone environment is refers to as single user, where on person can communicate with one computer only. There is no network environment.
We define multi-user processing system as a configuration in which many geographically dispersed or distributed independent computer systems are connected by a telecommunications network, and in which messages, processing tasks, programs, data, and other resources and transmitted between cooperating processors and terminals. Such as arrangement enables the sharing of many hardware and significant software resources among several users who may be sitting far away from each other.
Multiprogramming permits the running of several programs in the same time frame, or concurrently. That is, multiprogramming permits several unrelated programs, probably from many different users, to complete for the processor.
Although programs are said to run concurrently, this doesn't mean that they run simultaneously. Infect, the program take turns using the CPU. For example, one program could be using the CPU while an other program prints a record. The operating system keeps track of everything and makes sure that the programs don't get entangled (twisted, knotted). from the point of view of the user, his program was executed by the computer just as if the computer and all its resources belonged exclusively to that user. In reality, some times a computer is so overloaded that time delays make the shared nature of the machine more obvious.
Concurrent use of a single computer by many users, each heaving his own input/output devices, and accessibility to the computer at the same time, the computer in such cases gives each user a small, but frequently repeated slice of time, so that each user gets almost immediate response. This king of multiprogramming is called timesharing.
In the multiprocessing the CPU's of several computers are linked, or (the more modern alternative) the CPU of a single computer is provided with more than one arithmetic unit. These CPU's or arithmetic units operate in parallel, thereby allowing simultaneous execution of several programs or of several parts of the same program.
A computer system featuring more than one central processing unit in is called multiprocessing. In reality this system is consisted of two complete computers.
Multiprogramming is an operating systems capability that links together two or more CPUs to work in parallel in a single computer system. The operating system can assign multiple CPUs to execute different instructions from the same program or from different programs simultaneously, dividing the work between the CPUs. While multiprogramming uses concurrent processing with one CPU, multiprocessing uses simultaneous processing with multiple CPUs.
b. Device Drivers:
This software extends the capabilities of OS support I/O devices. Computer doesn't have IQ. It is the device driver that tells the computer that monochrome monitor is replaced with color monitor, sound card is attached to the CPU, fax modem card is linked with the computer etc.
c. Utility Software:
Be sure that utility programs are not part of the operating system. utility programs are provided with system software. Utility programs enhance the understanding and communication of users with computer. examples of utilities include:
Listing files and folders/directories
Comparison of contents
Deletion of files
Time and date facilities
Sorting files or data
Sending files to printer or any output devices