Computer Systems

Question 1

What is computer?

Answer 1

A computer is a machine that processes data

Question 2

Define hardware

Answer 2

The physical components that make up your computer system

Question 3

Define software

Answer 3

The programs that a computer system runs

Question 4

What is system software?

Answer 4

Systems software is software that controls the computer system and can control various hardware and other programs

Question 5

What is application software?

Answer 5

It is a type of computer program that performs a specific personal, educational and business function. Each program is designed to assist the user with a particular process

Question 7

Give some examples of application software

Answer 7

Word Processors Web browsers Email clients Games

Question 8

What is an embedded system?

Answer 8

Embedded systems are computers built into other devices

Question 9

Explain the role of the control unit in the CPU

Answer 9

To execute program instructions by following the fetch-decode-execute cycle Controls the flow of data inside the CPU (to registers, ALU, cache) and outside the CPU (to main memory and input/output devices)

Question 10

What does ALU stand for?

Answer 10

Arithmetic Logic Unit

Question 11

What does the ALU do?

Answer 11

Completes simple addition and subtraction Compares the size of numbers Can do multiplications and divisions using repeated addition and subtraction Performs logic operations such as AND, OR and NOT Performs binary shifts

Question 12

What is cache?

Answer 12

Very fast memory in the CPU

Question 13

What is cache used for?

Answer 13

To store regularly used data so that the CPU can access it quickly the next time its needed

Question 14

Describe the function of the clock

Answer 14

Used to synchronise when instructions will be carried out (like a metronome)

Question 15

What is a bus?

Answer 15

A collection of wires that are used to transmit data between components of the CPU and other parts of the computer system

Question 16

Describe what happens at each stage of the CPU fetch-decode-execute cycle

Answer 16

FETCH - The control unit reads the memory address of the next CPU instruction. The instruction stored in that address is copied from memory to one of the registers. The memory address in the control unit is incremented to point to the address of the next instruction, ready for the next cycle DECODE - The instruction that was copied from memory is decoded by the control unit. The control unit prepares for the next step EXECUTE - The instruction is performed

Question 17

What is volatile memory?

Answer 17

Temporary memory that requires power to retain its data

Question 18

What is non-volatile memory?

Answer 18

Permanent memory that keeps its contents even when it has no power

Question 19

What does RAM stand for

Answer 19

Random Access Memory

Question 20

Describe how RAM is used in a computer system

Answer 20

To store all data, files and programs when they’re being used

Question 21

What is ROM?

Answer 21

Read-only memory is a type of non-volatile memory used in computers and other electronic devices

Question 22

Explain why ROM is required by a computer system

Answer 22

It contains all the instructions a computer needs to properly boot up. These instructions are called the BIOS (basic input output system)

Question 23

Which usually has more RAM: an embedded system or a non-embedded system?

Answer 23

Non-embedded systems

Question 24

What characteristics of a processor may affect its performance?

Answer 24

Clock speed CPU cores Cache size Cache type

Question 25

Define primary storage

Answer 25

The memory areas that the CPU can access directly

Question 26

Define secondary storage

Answer 26

Non-volatile storage that isn’t directly accessible by the CPU

Question 27

Give some examples of primary storage

Answer 27

CPU registers Cache ROM RAM

Question 28

Give some examples of secondary storage

Answer 28

Magnetic hard disk drives Solid state drives CDs SD cards

Question 29

What are the advantages of a SSD compared to a HDD?

Answer 29

SSDs are faster SSDs don’t need defragmenting SSDs are more shock proof than HDDs HDDs make some noise, SSDs are silent

Question 30

What are the advantages of a HDD compared to a SSD?

Answer 30

HDDs are cheaper Both are high capacity, but HDDs are higher HDDs have a longer read/write life than SSDs - SSDs can only be written a certain number of time before they begin to deteriorate

Question 31

Why might someone choose magnetic tape as a form of storage?

Answer 31

It has a very high capacity and an extremely low cost per GB

Question 32

List some uses of flash memory

Answer 32

Cameras Smartphones Tablets

Question 33

What are the pros of optical disks?

Answer 33

They’re very cheap per GB Portable Won’t be damaged by water or shocks

Question 34

What are the cons of optical disks?

Answer 34

They are easily scratched Modern devices don’t have optical drives They can’t compete with flash storage devices due to their low capacity per disk, very slow read/write speeds and poor reliability of RW disks

Question 35

What are the pros of cloud storage?

Answer 35

Users can access files from any connected device Files can be shared with others or made public Easy to increase how much storage is available No need to buy expensive hardware to store data Cloud host provides security and backups for you

Question 36

What are the cons of cloud storage?

Answer 36

Need internet connection to access files Upload/download speed depends on bandwidth Stored data can be vulnerable to hackers Subscription fees for using cloud data may be expensive in the long term

Question 37

What are the functions of an operating system?

Answer 37

To communicate with input and output devices via device drivers Provide a platform for applications to run on, and a user interface Control memory management and allocation Organise the CPU and its processing tasks Deal with file management and disk management Manage system security and user accounts

Question 38

Explain how device drivers are used in a computer system

Answer 38

Device drivers act as a “translator” for the signals between the OS and the device

Question 39

Describe how the OS manages applications

Answer 39

Provides a platform for applications to run on and multitask Allows applications to access hardware, peripheral devices, RAM and secondary storage Provides a user interface that applications are accessed through

Question 40

Describe how the OS manages memory

Answer 40

Decides if applications or features have been used recently - if not they may be removed from memory Manages how much RAM a program has access to When running multiple applications at one, will make sure that they don’t overwrite or interfere with each other by allocating certain applications certain memory addresses, keeping their processes in separate locations

Question 41

Describe how the OS manages the CPU

Answer 41

Scheduling to determine the most efficient order for the CPU to execute instructions Interrupts the current CPU process if a higher-priority process becomes available

Question 42

Describe how the OS manages files and disk space

Answer 42

Manages the hard disk - splits the physical disk into storage sectors, decides which sector to write data to and keeps track of free space on the disk Organises and maintains the hard disk with utility software like defragmentation software

Question 43

Give ways in which an OS might keep your files secure

Answer 43

User account control Anti-theft measures Passwords Pins Fingerprint scanners Retina scanners

Question 44

List some types of utility software and explain what they do

Answer 44

Defragmentation- puts the files back into one block and collects the free space together Disk health - scans the drive for problems and fixes issues where possible Compression - reduces the size of files so they take up less disk space Encryption - scrambles (encrypts) data to stop third-partners from accessing it Backup - copies the computer system’s files and settings and stores them externally so that they can be restored in the event of data loss Virus scanners - inspects each file on your computer, looking for virus System cleanup - goes through and gets rid of temporary files left on your hard drive which can end up taking up lots of space unnecessarily

Question 46

Give some examples of system software

Answer 46

Operating systems Utilities

Question 47

What is the Von Neumann architecture

Answer 47

It consists of a single shaped memory for programs and data, a single bus for memory access, an arithmetic unit and a program control unit.

Question 48

AND gates

Answer 48

Question 49

NOT gates

Answer 49

Question 50

OR gates

Answer 50

Question 51

NOR gates

Answer 51

Question 52

How does a magnetic hard drive operate?

Answer 52

It consists of a number of disks coated in a magnetic material. They spin at around 7200 rpm. The data is encoded into bits and written onto the surface as a series of changes in the direction of the magnetisation.

Question 53

How does optical storage work?

Answer 53

Data is written onto the disc by a laser and is read from the disc by another laser.

Question 54

How do SSDs work?

Answer 54

There are no moving parts, unlike the spinning disc inside a magnetic drive. A SSD uses microscopic electronic switches to store data. SSDs use switches called floating gate transistors. These create a special cage (the gate) that traps the electron flow within it.