Software refers to the instructions that command a computer to perform a desired tasl. Sometimes people use the terms programme, package and application to refer to software products, although is slightly different.
Commputers require software to perform every task they do. For example, computer software allows a user to type, edit and print a document.
The are 3 types of software:
1) The operating system (OS) such as Windows2000, Windows XP, Linux and AppleOS performs the most basic tasks required to keep a computer running. These tasks include organising computer files, allocating computer memory, managing the interface between the computer and the network, and scheduling the computer to run othe software.
2) Application software satisfies specific users, including database management, business functions and the interface between the user and the software. When you use a word processor to create a document or a speadsheet to help analyse data, you are using an application software.
3) Programming language are also considered software and they enable the development of other software. eg. C language, VisualBasic, JavaScript, HTML, CASE toold etc.
Make or Buy Decision?
Organisations face the decision whether to
a) buy packaged software without modification
b) by packaged software but with modification or customised.
c) develop the software from scratch.
Package software: off the shelf software exists for a range of uses; low price, extensive features and high reliability. Diadvantage: rely on one company, incur costs in licensing, training and upgrades may be expensive.
Customised software: may reduce dependence on one company, meet the special needs of the organisation.
Custom software: here the organisation develops its own software, expensive, integrated solutions.
Generations of Programming Languages
1st generation - Machine Language based on the binary system of 1 and 0.
2nd generation - Assembly language -required programmers to specify in painstaking detail every step they wanted the computer to perform.
3rd generation - such as COBOL, FORTran, Pascal, C++, VisualBasic included more powerful commands. eg. a single command might require 10-50 second generation commands.
4th generation - such as Access2000 Database, Oracle database - a single commmad often equals hundred and even thousands of instructions written in a second generation language.
Operating Systems
A computer operating system (OS) is a suite of programmes (modules) that provide the necessary interface between user programmes and the computer hardware. It provides a variety of services to assist users to perform their tasks. The OS system basically provides an environment so that users can process their data conveniently. It simplifies the task of preparing and running an application on a computer. The OS must supervise and manage the computer resources (such as the procssor, memory, input/output devices) optimally. It must also schedule and execute both user and system tasks (or processes) in a fair and orderly manner. It must also provide data security as well as allow users to share information.
Examples of OS
a) MS-DOS has probably been the most widely used OS on personal computers (IBM and its clones) until now; it was created by Microsoft Corporation. DOS is a single-user, single-tasking OS. Most of the time, all the user sees on the screen is the DOS command prompt (eg. C:\>). To carry out a task, the user must type in a DOS command such as DIR (listing files in a directory) or DEL (deleting files). DOS was originally designed for the Intel 8086 processor. It served its purpose well, but it was found to be inadequate for the most powerful processors (eg. 80386, 80486, Pentium II, etc.). The DOS architecture as originally designed, could not take advantage of the new features found in these processors (eg. improved memeory addressing capability). Also, DOS was not user-friendly.
b) Windows 3.1 is not really an OS by itself. It is a software which rus on top of DOS, i.e. you must first load DOS before you can use Windows. Windows provides a graphical user interface (GUI) operating environment. Most of the commands are executed by pointing at icons and test and clicking on them by using a mouse. The applications are grouped so that they are easy to use. Windows is also a single-user system but with multitasking capability. The programme that is currently executed in the active window is called the foreground job and all other running programmes run in the background, called background jobs.
c) Windows 95 / 98 are single-user multitasking system systems and use GUI. But unlike Windows 3.1, these OSs are true operating systems that run on themselves.
d) Windows NT is called a network operating system (NOS) is muti-user, multitasking operating system for connecting computers on a local area network (LAN). It is a multi-platform operating system in that it can execute applications developed under other operating system platforms such as DOS, Windows 3.1 and UNIX. The system requires more memory to run efficiently and require more storage space.
e) Novell is also a LAN or networking software and like WinNT, it provides many useful se4vices to users at the workstations.
f) UNIX is a multi-user, multitasking operating system and developed at Bell Laboratories in the 70s. The OS can be ported to different machines quite easily. UNIX is being used on a wide variety of computers ranging from very large supercomputers to microcomputers.
Continued
Soalan 6:
Apakah perbezaan antara jenis-jenis perisian yang terdapat dalam sistem komputer sebuah sekolah?
