Chapter 8 - Types of operating systems

Parallel processing (task split into several tasks) system spreads load over multiple servers – single job split into several tasks and run on a separate computer e.g. intranet – cluster of servers share memory and tasks

many jobs run simultaneously on standalone computer – switches between them e.g. listening to music, checking emails occasionally time-sharing systems – single supercomputer is connected to terminals each user gets a slice of processor time according to scheduling algorithm.

Mobile operating systems – combine features of PC OS with special features e.g. cellular/wireless connectivity, phone access Main OS + low-level proprietary real-time OS – operates radio and other hardware, security vulnerabilities (others can gain control of phone)

Basic household appliances – minimal user interface (few buttons), accepts inputs and sends outputs, no complex memory management (limited RAM) Uses ROM - software doesn’t need constant updating, data not deleted when switched off On aircraft/safety-critical system – respond quickly to many inputs simultaneously, failsafe mechanisms (detect + take action if a hardware component fails)

Stored in EPROM (Erasable Programmable ROM) Initialises + tests system hardware, loads OS onto RAM from hard disk

Program provided a software interface to a particular hardware device – enables OS to access hardware functions Hardware dependent + OS specific Communicates with device via system bus

A virtual machine is an emulation of a computer system that can be made to run on a different computer.