Chapter 8 - Types of operating systems

Question 1

Distributing OS

Answer 1

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

Question 2

Multitasking system + Multi-user, multitasking system

Answer 2

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.

Question 3

OS used by mobile phones

Answer 3

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)

Question 4

Embedded OS + Real-time OS

Answer 4

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)

Question 5

BIOS

Answer 5

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

Question 6

Device drivers

Answer 6

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

Question 7

Virtual machine

Answer 7

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