Software, the OS and interrupts
Software and the operating system
- Hardware is the physical parts; software is the programs that control them.
- Software splits into system software and application software.
- The most important system software is the operating system.
System vs application software
- System software controls the computer and gives a base for other programs: the operating system, compilers, device drivers, and utility software (anti-virus, backup).
- Application software lets the user do a task: word processor, spreadsheet, database, web browser.
- System software runs in the background; application software is used directly by the user.
Practice
Which is system software?
The OS (and drivers, utilities) is system software; the others are application software.
Practice
Sort these into system or application software.
Drivers and utilities run the computer (system); a browser is a user application.
The operating system
- The OS controls the whole computer so the hardware, applications and user work together. Its roles include:
- managing files, managing memory, managing peripherals (and drivers), multitasking, handling interrupts, providing a user interface, a platform for applications, and security.
Practice
Which is a role of the operating system?
The OS manages files, memory, peripherals, multitasking, interrupts, the UI and security.
Interrupts
- An interrupt is a signal to the processor that something needs attention now.
- It can come from hardware (a key pressed, printer out of paper), software (divide by zero), or the user (pressing cancel).
- The processor stops, saves its place, services the interrupt, then resumes — so the computer reacts quickly to important events.
Practice
An interrupt is:
An interrupt makes the CPU pause, service the event, then resume — for quick reactions.
Practice
Which is an example of a hardware interrupt?
A printer out of paper is hardware; divide-by-zero is software; pressing cancel is a user interrupt.
You've got it
Key idea
- system software runs the computer (OS, drivers, utilities); application software does a user task
- the OS manages files, memory, peripherals, multitasking, interrupts, the UI and security
- an interrupt = a signal needing immediate attention (hardware / software / user)
- on an interrupt the CPU saves its place, services it, then carries on