The term software means the digital components of a computer system. This includes all of the programs and applications which can be run on the computer. There are two main types of software we need to be aware of, application and systems.

This is a term given to software that has been developed to allow a user to complete  a certain task. 30 years ago people used to use typewriters to create letters and reports. When computers were developed they created word processing software to allow us to create letters and reports on the computer.

All application software has a purpose, ie a task of value it enables humans to do. Examples include Spreadsheet software, Database software, Games, Photo editing software and many more.

This is software that has been developed to ensure the computer runs as efficiently as possible.

A computer needs system software to enable users to operate it and install other programs (application software). An operating system is a type of system software. Examples of common operating systems are Windows (developed by Microsoft) and Mac Os X (developed by Apple). 

Functions of system software System software involves 4 areas: 

1. Running the computer (operating system software) 

2. Providing other useful functions for operating the computer (utility programs) 

3. Providing for frequently required tasks (library programs) 

4. Enabling software to be produced (compilers and interpreters).

5.Providing a user interface

6.Managing hardware

7.Managing Software

Operating system software allocates memory for each task a computer is completing and provides a user interface so the human can interact with the computer.

It also controls communication with resources, such as input and output devices and manages security measures, such as user access through accounts. 

Utility programs perform functions which are to meet a specific need, for example changing the screen resolution, performing a file backup process or virus checking. 

Library programs are precompiled pieces of code which can be included by a user when creating their own programs. A compiler is a program which will translate a program from high level language (such as C or Pascal) into machine code for the computer to execute. 

Memory is the part of the Central Processing Unit (CPU) that stores data for use by the processors. The data used can be program files or data files used by the programs. Computer memory is divided into RAM, ROM and Cache memory. Memory is volatile meaning when it loses power the data is lost. If we wish to use the data again in the future we must save it to a storage device such as a hard drive or pen drive.

The main memory in a computer consists of 2 microchips in the CPU called RAM and ROM.

RAM

Random Access Memory (RAM) is used for holding programs and data that the user is working with. RAM can be written to as well as read from. When the computer is switched off, the contents of RAM are lost. This sort of temporary memory is called volatile memory. Larger RAM capacity will mean faster processing speeds.

ROM

Programs and data stored in ROM can be read from but cannot be written to. The programs stored in ROM are permanent. The main use of ROM is to store the ‘booting up’ or BIOS (Basic Input/ Output System) - the software used to load up the Operating System and let the different parts of your computer communicate. 

CACHE

The cache is a special type of computer memory which is similar to RAM, as cache memory can be written to as well as read from. The CPU looks in the cache for the data it needs. If the data is there, it will retrieve it and process it. The purpose of cache memory is to store frequently accessed programs or instructions. Cache memory is also volatile. 

The operating system monitors whether external storage devices are connected and controls how data is saved to different areas. The operating system (OS) manages how full a storage location is and whether there is sufficient space to save a file in its specified location. The OS provides file management services by allocating where data is stored on the disk drives and memory. This allocation is important because it allows the computer to find the files a user makes a request to open. 

A process is an activity that is carried out as part of a computer system. System software allocates the time needed by the CPU to process the instructions of a computer program as efficiently as possible. A computer may have several different tasks to run at the same time - known as multi-tasking. In the event of multi-tasking, the system software manages how the processor switches between different computer programs. When there are lots of programs running, the processor can become overworked and some programs may appear to be running slower than normal. 

A processing mode is the way in which the processing tasks carried out by a computer system are organised to make the most of the potential of the following three modes of processing are used in systems with distinct requirements and are best suited to different applications. There are 3 modes we need to be aware of.

Real Time Processing

Batch Processing

Muliti-User Processing 

Real-time processing is when the system is processing data fast enough to influence behaviour in the outside world. This can be carried out by using a record blocking system, where users are given exclusive access to a small set of records for a short period of time to process or make changes. The advantage of real-time processing is that the system can cope with lots of changes or processes in a short space of time. For that reason, it is frequently used for booking systems, for example online ticket sales or airline sales. It is also essential for the safe running of systems like air traffic control. A disadvantage is that there will be a limit to the number of users or task who can access the system so some users must wait. 

Batch processing is when all the data to be input is collected together before being processed as a single operation. The processing is usually scheduled to happen during processor downtime, for example overnight, while a limited number or no users are accessing the system. Batch processing systems are used for tasks such as processing bank or credit card statements, generating billing information for gas or electricity readings. In the case of gas or electricity billing, the company hold a permanent master file for each customer. The meter readings are held in a temporary transaction file, sorted and merged with the master file to update the meter reading for each customer and generate a bill. This is an efficient processing method for repeated tasks, for example processing bank statements at the end of each month, because they can be carried out quickly without user interaction. The disadvantage of this mode of processing is that it is dependent on the data being accurate when input, as errors can cause the processing to crash. 

Multi-user processing is when several users appear to have individual control of the system at the same time. It is implemented by using time slices, an allocated length of time for each program or user. This gives the appearance that multiple users are working on different tasks simultaneously but the central processor is switching between tasks at high speed, with only one program being executed at a time. The advantage of this mode of processing is that the processor can be used to execute multiple programs with the appearance of simultaneous usage. 

This is a program that comes with the computer system –“a systems program”. It performs specific tasks while the computer is operational. 

For example it will back up files, check for virus’ or run a compression program. Some of the specific applications carried out by the utility program are: 

• Disk defragmenting 

• Task scheduling 

• Backup 

• Restoring data 

Files on a computer are stored on the hard disk. As more and more files are saved to the hard disk sections of files get stored away from each other, which causes the computer performance to slow down. The computer slows down because the hard disk has to find all the data from each file before it can be opened. Large files are often fragmented, disc defragmenter can be used to rearrange data/store files in blocks together which frees up storage space and speeds up time to access data. 

This is when the CPU will allocate time for each task or program that the computer has running. This ensures that many programs can seemingly run at the same time and that maximum usage is made of the CPU time. You can use the task scheduler to ask the computer to perform specific tasks at times you choose for example setting it to run your antivirus software or perform back ups over night. 

This involves making copies of files or programs in case the original one becomes corrupted. Backups should be made at regular intervals to ensure you always have an up-to-date copy of your files. A backup of software should be stored separately from the computer to protect against dangers such as fire. There are different types of backups that can be made. Full Backup This copies all files to provide a complete record of the data. Differential Backup This copies files that have changed since the last full backup. Incremental backup This copies only those files that have changed since the last backup. This could be a full backup or a previous incremental backup. Journal file This provides a record of operations since the previous backup. Hard Copy As a last resort a copy store on paper. 

This is used when files or programs become corrupt. The backup system files are copied back onto the system. To return the system to the state before it failed involves restoring the latest journal file or any transactions files. 

Antivirus software is used to detect and quarantine or remove malicious software from the computer system. Antivirus monitors are stored in the hard drive; they continually monitor the system for the presence of a virus. If one is detected the file is prevented from running and a warning message is sent to the user. The user can then decide whether to quarantine or remove the software. Virus checking scans all files including new data read into the computer, to detect any viruses. Disinfection is the removal of any detected viruses. Quarantine is isolating any files that are suspected of containing a virus. 

Regular updates of antivirus software are essential to ensure that the computer system is completely protected against any threats. New viruses are created everyday so it is important that the antivirus software can detect these as soon as possible and take any necessary action.