My Science School

Computer software is a set of instructions called programs which are fed into a computer to enable it to perform certain specific tasks. Some of these programs called applications, or user software, are written in any of the different computer languages, such as C, PASCAL, FORTRAN or BASIC. These programs can be of any size. Student programs for small numerical problems may consist of only 5 to 20 statements, whereas the accounting and management information programs that are used by large corporation or governments may have thousand of statements.

Different from this class of software is the system software which includes programs that translate user programs into machine language programs and then load these translated programs into main memory prior to execution. System software also includes the set of certain routines required to manage the operation of the physical resources such as the central processing unit, mass storage and input-output devices.

Ready-to-use software that is floppy disks with different programs are available today. On loading these programs in a computer, instructions for using that program appear on the screen and can be used straight away.

A microcomputer is a computer which uses a microprocessor for its central processing unit. Computers, in their early stages, were unlike what they are today. Instead of occupying a desk-top, they needed large halls to house. This was because they used large and bulky vacuum tubes or electronic valves. In the late sixties, with the advent of semiconductor materials like germanium and silicon, small, effective, cheaper and robust micro-devices like the transistors and the chip were developed.

A typical chip, of the size of a thumbnail, contained a number of transistors, diodes, varistors, etc. This chip not only reduced the size of the computers but also enhanced the power of the computer to a great extent. This development of computers from a room size to pocket-size took place in different stages of integration and miniaturization of electronic components. These different stages of integration are popularly known as SSI, VLSI and ULSI (small-scale, very-large-scale and ultra-large-scale integration respectively) in the electronic industry.

A microcomputer consists of a microprocessor, input or output devices, memory unit and typical connecting links called system buses.

LAN is the short form of Local Area Network. It allows the linking together of several computers within a building. This interconnection of various computer terminals located in close proximity such as an industrial complex, an office building and a university campus enables each terminal to interact with any other. LAN is, therefore, a multi-user system. Not only is the exchange of data among the various linked up computers made possible by LAN but resources from a large computer can also be shared. LAN thus offers the most effective means of handling local automated tasks and data management.

LAN can be even linked with an outside computer network using ‘gateway’. The gateway converts the formats of data to make them compatible to the two networks. 

A computer virus is a self-replicating computer program or a segment of code that inserts copies of itself into other programs, thus infecting them. As a result, the original programs cannot run smoothly, thereby totally disrupting the functioning of the computer.

When an infected program is run on a computer, the hidden virus is activated and attempts to inject itself into additional programs. This process is analogous to the biological process of virus spreading from cell-to-cell within an organism. Very much like the biological virus, a single computer virus can spread to any number of compatible computer systems if provided with a pathway for infection.

The virus infects a system through sharing of infected diskette or through communication links, like local area networks or programs transmitted from distant systems.

Some of the commonly destructive manifestations of a computer virus include erasure of recorded data, rendering of entire device drives unreadable, interfering with communication and breaking the security cordon of the host computer. The virus may also create other problems such as display of unusual messages or plotting the text backward. Some of the well-known viruses are Pakistani Brain, Lehigh, Friday the 13th, Christmas and Bloody.

CAD and CAM are abbreviations for ‘Computer Aided Design’ and ‘Computer Aided Manufacture’ respectively. Both are basically computer programs — sets of instructions —used to create drawings or to assist in manufacture of goods. Through a CAD program rough sketches are initially made on a computer screen by using a light pen or a mouse, which can further be finalized in exact details. The final drawings can thereafter be stored in computer memory in entirety or in parts for future use. Alterations or updating can subsequently be easily made in the final drawings. CAD programs are sometimes made for specific purposes such as designing printed circuit boards and computer chips. A CAM program, on the other hand, is used in the manufacture of goods in industries. For instance, computer-driven lathes, drills, welding machine or robotically operated production lines can be employed in factories to speedily manufacture a wide range of precision produced goods.