4.1 Types of Software & Interrupts


System & Application Software

The system software provides the services that the computer requires (e.g. OS & utility software). Without this, a system is useless.

Utility Software

Utility software performs specific tasks. They help configure the system, analyse it and optimise it to improve efficiency.

Security Utilities

  • Antivirus -> scans the system and ensure that files are safe from malware

  • Encryption -> uses an algorithm to encrypt a file to make it unreadable

  • Firewall -> monitors network traffic and blocks unauthorised access

Disk Organisation Utilities

  • System clean-up tools -> removes files that are no longer needed to reduce storage space

  • Disk defragmentation tools -> rearranges the parts of files on a disk drive

Data Compression Utilities

  • File compression software -> makes files smaller to take up less storage space

File Backup Utilities

  • Full backup -> stores all files and software on the system

  • Incremental backup -> only backs up files and software that have been added since the last backup (more efficient)

Application Software

These are designed to carry out specific tasks. They are the applications that the OS would process and allow users to complete their tasks.

Word processing software -> allows users to create documents Spreadsheet software -> another documents where mathematical calculations are key Presentation software -> allows users to create presentations for an audience Multimedia software -> used to create interactive content, to do with photography and videography Web browsers -> for users to access the internet

Do not use the Microsoft terms in the exam as this will cost you marks!!!

Distribution Methods

  1. Free software -> user can access source code, cost to buy, has the right to edit the software

  2. Freeware software -> user cannot access source code but is free to use, no right to edit

  3. Shareware software -> user is given a trial version of the software for a limited time

  4. Paid software -> user pays a fee to use the software

Know the ethical considerations when distributing software as you may be asked about it.


The Operating System

The OS can do various things such as:

  • Managing files

  • Handing interrupts

  • Providing an interface

  • Managing peripherals and drivers

  • Managing memory

  • Manage multitasking

  • Providing a platform for running applications

  • Providing a system security

  • Managing user accounts

How it all links together?

The hardware has some firmware on it which loads the operating system. In turn, the OS loads the application software. A device is powered off in the same sequence but backwards.

Sample answer:

Performs basic functions of a computer Manages the hardware Provides a platform to run software Provides a user interface


Interrupts

Interrupts will need to ensure that the CPU can stop executing its current program to run code for the overall interruption. Interrupts need to be added to an area called the interrupt service routine.

There are two types of interrupt:

  1. Hardware interrupt (i.e. moving the mouse or pressing something on a keyboard)

  2. Software interrupt (i.e. a program doesn't respond)

The interrupt service routine is simply added to a particular area where a certain set of instructions are sent that will need to be fetched, decoded and executed to complete the commands of the interrupt.

Sample answer:

An interrupt signal is sent to the CPU or processor CPU stops the task its currently doing to service the interrupt An interrupt service routine is used to service the interrupt A message is displayed to the user to notify them


Exam Questions


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