Cambridge O Level Computer Science · Syllabus 2210 · Software
Application Software
What is Application Software?
Application software is software that provides the services the user requires, performing user-oriented tasks such as word processing, spreadsheets, databases, browsing, graphics, media and games. It runs on, and requests resources through, the operating system.
This definition is part of the Software chapter in Cambridge O Level Computer Science.
Application Software in context
A computer is built in layers, and each layer only works because the layer beneath it is already running. Hardware executes machine instructions and nothing else. Firmware, held in non-volatile memory, starts the hardware and its bootloader loads the operating system. The operating system then manages files, memory, peripherals, users and security, and provides the platform on which application software runs. While all of that is happening, interrupts let an urgent event — a key press, a division by zero — reach the CPU without it having to keep asking. And because a CPU can only execute machine code, every program a person writes must first be put through a translator: an assembler, a compiler or an interpreter.
Application software provides the services that the user requires. It performs the tasks a person actually wants done — writing a letter, editing a photograph, keeping accounts, browsing the web, designing a part, playing a game. Application software cannot reach the hardware on its own: it depends on the system software beneath it, and requests every file, every allocation of memory and every use of a device through the operating system.
An operating system is system software that manages the computer's hardware and resources and provides a platform on which application software can run. It is not one job but nine, carried out at the same time and constantly interacting: managing files, handling interrupts, providing an interface, managing peripherals and drivers, managing memory, managing multitasking, providing a platform for running applications, providing system security, and managing user accounts. Every one of those functions exists because a shared machine with limited resources needs someone to be in charge of them.
Application software cannot run on its own. Applications run on the operating system; the operating system runs on the firmware; and the bootloader — which is part of the firmware — runs on the hardware. Each layer depends on the one below it being present and working. Firmware is the only software that is already there when the power arrives, which is why it, and not the operating system, is what starts the machine.
Common mistakes with Application Software
- 2. Defining application software as "software the user installs". Why it fails A user can install anti-malware, a compression tool or a device driver — all system software. A manufacturer can pre-install a browser and a media player — both application software. Who installed it is irrelevant. Fix Ask what the software is for. Services the computer requires, or services the user requires? See section 4.1 C.
- M1. "The operating system is application software." Why it fails Application software provides the services the user requires. An operating system provides the services the computer requires, and applications run on it. Putting it in the wrong category inverts the whole layer model. Corrected model An operating system is system software. It manages the hardware and resources and provides the platform on which application software runs. Exam-safe sentence "An operating system is system software, because it provides the services the computer requires and gives application software a platform to run on." Show the retrieval checkHide the check Check: Which category does an operating system belong to, and what is the test?Answer: System software. The test is whose requirement it serves — the computer's, not the user's.
Questions students ask about Application Software
What is the difference between system software and application software?
System software provides the services the computer itself requires: it manages the hardware and provides the platform other software runs on, and includes the operating system and utility software. Application software provides the services the user requires, performing tasks such as word processing, browsing or games, and it depends on the system software beneath it for every file, memory allocation and device it uses. Who installed the software, or where it came from, decides nothing — only what it is for.