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AQA 7517 · Paper 2 · 4.6.1

System & Application
Software

OS, utilities, translators · Application software categories · Section 4.6

WHAT YOU'LL LEARN
System vs application software · OS functions · Utility software · Open vs proprietary
AQA SPEC LINK
4.6.1 — Role and function of operating systems; system and application software
Two Categories

System vs Application Software

SYSTEM SOFTWARE
Software that manages and controls computer hardware, providing a platform for application software to run. Operates below the application layer.
APPLICATION SOFTWARE
Software designed for end users to perform specific tasks. Runs on top of system software. Examples: Word, Chrome, Photoshop, games.
System Software Types

Types of System Software

Operating System (OS)
Manages hardware, provides user interface, runs programs. Windows, macOS, Linux, Android
Utility Software
Maintenance tasks: antivirus, disk defragmenter, backup tools, compression utilities, encryption tools
Translators
Compilers, interpreters, assemblers — convert source code to machine code
OS Functions

What the Operating System Does

Memory management — allocates RAM to processes; virtual memory using page files
Process management — scheduling CPU time; multitasking; process states
File management — organises storage, directories, permissions, file operations
Device management — drivers for hardware; I/O buffering; plug-and-play
Security — user authentication, access control, firewalls, encryption
User interface — CLI (command line) or GUI (graphical user interface)
Application Software

Types of Application Software

General purpose — word processors, spreadsheets, databases, browsers (Microsoft Office, LibreOffice)
Special purpose — designed for one specific task (Photoshop for image editing, AutoCAD for design)
Bespoke software — custom built for one client/organisation; expensive but precisely tailored
Open source — source code freely available; community developed (Linux, Firefox, GIMP)
Proprietary — source code closed; must pay to use (Windows, Adobe Photoshop)
Open vs Proprietary

Open Source vs Proprietary Software

FeatureOpen SourceProprietary
CostUsually freePaid licence
Source codeAvailableHidden
ModifyYesNo
SupportCommunityOfficial (paid)
Utility Software

Key Utility Programs

Antivirus — detects and removes malware using signature databases and heuristic analysis
Disk defragmenter — reorganises fragmented files on HDD so they're stored contiguously (not needed for SSDs)
Backup software — full, incremental, or differential backups to prevent data loss
Encryption utilities — encrypt files/drives (BitLocker, VeraCrypt)
Disk compression — compress files to save space (ZIP, NTFS compression)
Bespoke Software

Custom-Built Software

Bespoke software is created specifically for one organisation. Examples: NHS patient management systems, airline booking systems, HMRC tax systems.
ADVANTAGES
Exactly matches requirements · No unnecessary features · Can be integrated with existing systems
DISADVANTAGES
Very expensive · Long development time · May have bugs with no large user base to test
AQA Exam Style

Practice Question

AQA 7517 — Paper 2 Style
(a) Distinguish between system software and application software. [2]
(b) Give THREE functions of an operating system. [3]
(c) A hospital commissions bespoke software for patient records. State ONE advantage and ONE disadvantage of bespoke software over off-the-shelf software. [2]
(d) Explain the difference between open source and proprietary software. [2]
[9 marks]
2 marks
(a) System software manages/controls hardware and provides a platform [1]; application software is used by end users to perform specific tasks and runs on top of system software [1]
3 marks
(b) Any 3 of: memory management / process management / file management / device management / user interface / security/access control
2 marks
(c) Advantage: exactly meets requirements [1]. Disadvantage: more expensive / takes longer to develop [1]
2 marks
(d) Open source: source code is freely available and can be modified [1]. Proprietary: source code is kept secret; users must pay for a licence [1]
Summary

Key Points to Remember

System software — OS, utilities, translators; manages hardware; runs beneath apps
Application software — general purpose, special purpose, bespoke; used by end users
OS functions — memory, process, file, device management + UI + security
Open source — free, modifiable; proprietary — closed, licensed
Utility software: antivirus, defragmenter, backup, encryption, compression
🎉 Lesson complete — move to the quiz!