Software classification

System software manages the computer system resources and acts as a platform to run application software — for example the operating system (1).

Application software performs end-user tasks — jobs the user wants done, such as a word processor or a web browser (1). (2)

(a) Application software — it performs an end-user task (1) (b) System software — antivirus is a utility program that maintains and protects the system (1) (c) System software — a driver allows the OS to communicate with a hardware device (1) (d) Application software — it performs an end-user task (1) (4)

The operating system handles management of:

1. Processor(s) (1)
2. Memory (1)
3. Input/output (I/O) devices (1)
4. Applications (1)
5. Security (1)

(5)

(a) A utility program is software that performs maintenance tasks to keep the computer system running efficiently and securely (1). It is system software, because it maintains the system rather than performing an end-user task (1).

(b) Three examples:

• Antivirus — scans for and removes malicious software, protecting the system and its data (1)
• Backup — copies files to a second location so they can be recovered if the originals are lost, deleted or corrupted (1)
• Defragmentation — reorganises files on a magnetic hard disk so each is stored contiguously, reducing the movement of the read/write head and speeding up access (1)

(Other valid utilities: compression, disk clean-up, encryption, file management.)

Memory management. The operating system allocates an area of main memory to each running program so it has space to store its instructions and data (1). It also keeps those areas separate, so that one program cannot overwrite another's data — which prevents one badly behaved program from crashing others (1).

Processor management. The OS decides which program gets processor time and for how long, switching rapidly between them (1). This allows several programs to appear to run at the same time, even though the processor can only execute one instruction stream at a time per core (1).

Without this management, only a single program could run at once, and running programs could overwrite each other's memory, making the system unstable and prone to crashing (1).

(a) System software — specifically a utility program (1). It maintains the system by reducing file sizes to save storage space, rather than performing a task the user set out to accomplish (1).

(b) Application software (1). It performs an end-user task — editing photographs is precisely the job the user wants done (1).

(c) System software (1). It manages the computer system's resources — the processor, memory, I/O devices, applications and security — and acts as a platform on which application software runs.

Problem 1 — applications could not be run. The operating system manages applications, loading them into memory, running them and closing them cleanly (1). With no OS there would be no mechanism to start a program at all, so the installed software could never be launched (1).

Problem 2 — no communication with hardware. The OS manages input/output devices, using device drivers to communicate with printers, monitors and storage (1). Without it, every application would need to include its own code for every possible device it might encounter, which would be impractical and hugely duplicated across programs (1).

Problem 3 — no memory or processor management. The OS allocates memory to each program and decides which gets processor time (1). Without this, only one program could run at a time, and running programs could overwrite one another's data, making the system unstable (1).

(Also creditworthy: no security — no user accounts, passwords or access rights — and no user interface through which to interact with the machine at all.)

Purpose. System software manages the computer system's resources — the processor, memory, I/O devices, applications and security — and acts as a platform on which other software runs (1). Application software, by contrast, performs end-user tasks: the jobs a person actually wants the computer to do (1).

Examples. System software includes the operating system, utility programs such as antivirus and backup, and device drivers. Application software includes web browsers, word processors, spreadsheets and games (1).

Relationship — dependency. Application software cannot run without system software beneath it: it needs the operating system to load it into memory, allocate processor time and give it access to files and devices (1). The dependency is one-way — system software can run perfectly well with no applications installed, it simply would not be doing anything useful for the user (1).

Relationship — abstraction. System software also hides the complexity of the hardware, so an application can save a file without knowing whether the storage is a hard disk, an SSD or a network drive — it simply asks the operating system, which handles the detail (1).

There is some truth in the statement: utility programs are not required for a computer to function from moment to moment, since the operating system handles the essential management of processor, memory and devices (1).

However, utilities protect against problems that have not happened yet. Antivirus guards against malware, which can arrive at any moment through a download or an email regardless of how well the machine currently works (1). Backup protects against hardware failure, accidental deletion or ransomware — a computer working perfectly today gives no protection against a disk failing tomorrow, and without a backup that data is simply gone (1). Disk clean-up removes the temporary files that accumulate over time and would eventually fill the storage (1).

One case where a utility genuinely is not needed: defragmentation on a computer with an SSD (1). Solid-state storage has no moving parts, so fragmentation does not slow access down — and running a defragmentation tool would cause unnecessary rewriting that shortens the drive's lifespan, making it actively harmful rather than merely pointless (1).