Topic 3.2 Functions of commonly used programs

Topic 3.2 Functions of commonly used programs

1. Libraries

   • A library is a collection of commonly used private functions and subprograms. Examples of private functions include standard mathematical operations such as square root, random number generators. Examples of subprograms include standard input/output routines, such as saving data to disk. These functions and subprograms can be called from within your program anytime, but only when the appropriate library has been linked
   • The advantages of using standard libraries
     • • related private functions and subprograms are stored in the same location
     • • time is saved as the programmer can simply use the private functions and programs stored in a library
     • • subroutines contained in a library have already been tested, so they should work reliably and not need further testing
     • • programs will contain less code and will therefore be easier to maintain

2. Software development environment

   • Software development environments, also known as Integrated Development Environments (IDE), provide programmers with various tools that are needed to create computer programs. Here are some of the tools and facilities offered by software development environments

3. Disk organisation

   • File transfer
     • File transfer is the ability to transfer data from one location to another. This can be done by simply copying a file from one folder (directory) to another, or from one storage medium to another. You may wish to carry out either of these tasks in order to organise your files better, using subfolders or to back-up your work onto a secondary storage device, such as a flash memory stick.
   • Formatting
     • Formatting is the process of preparing a disk for use. During this process, a new file system is set out on disk and all data may be erased in readiness for new data to be stored.
   • Compressing
     • Compression is the process of making a file size smaller. This may be advantageous as it allows more data to be stored on the disk and files may also be transferred more quickly. There are two methods of achieving disk compression; one is software based and the other hardware based.
       • Software based disk compression is often included as a facility of an operating system and so it is readily available on most computer systems. The disadvantage of this is that it slows down the process of reading and writing to disk.
       • Hardware disk compression requires specialist hardware, which can be expensive. However, it does not affect the speed of access as much as software based disk compression.

4. Disk organisation

   • System Restore
     • System restore is the process of replacing lost or corrupt data by replacing it with an earlier backup.
   • Disk Defragmentation
     • Files are stored on computer systems that can, over time, become fragmented. This means that they are split and stored on different parts of the disk. If a file is fragmented, it takes longer for the disk heads to move between parts of the file, which slows the process of loading it.
     • Defragmentation is the process where files are physically re-arranged on disk so that they are no longer fragmented and the parts of each file are stored together. This improves the speed of accessing data from disk.
   • Control panel
     • Many operating systems use a control panel to give the user control of software and hardware features. It enables the user to change settings, such as sound, device and display settings all from one convenient location.
   • Virus Protection
     • A virus is a computer program that is able to copy itself onto other programs often with the intention of maliciously damaging data. The consequences of a virus spreading can have catastrophic effects on computer systems, and therefore need to be prevented.
       • Virus protection software, also called anti-virus software, is a program that can be loaded into memory when the computer is running. It monitors activity on a computer system for the signs of virus infection. Each virus has its own unique ‘signature’ which is known to virus protection software and stored in a database. Data stored on a computer system is scanned to see if any of the virus signatures within the database exist on the system
   • Firewall
     • A firewall can be a software or hardware security system that controls the incoming and outgoing network traffic. Packets of data are analysed to determine whether they should be allowed through or not.

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