Hardware

Question 1

CPU

Answer 1

Central Processing Unit - Responsible for computer’s processing

Question 2

ALU

Answer 2

Arithmetic Logic Unit - Carries out logical, shift, and arithmetic operations

Question 3

CU

Answer 3

Control Unit - Coordinates CPU activities

Question 4

General Purpose Register

Answer 4

Small amounts of memory in CPU that hold data

Question 5

Accumulator

Answer 5

Temporarily stores results of arithmetic + logic operations

Question 6

PC

Answer 6

Progam Counter - Stores address of next instruction to be executed
1) Incremented after instruction fetched
2) Points to next instruction to be executed

Question 7

Von Neumann architecture

Answer 7

Storing program and data in the same memory

Question 8

CIR

Answer 8

Current Instruction Register - Stores current instruction to be executed

Question 9

Memory Registers

Answer 9

Memory Address Register (MAR) and Memory Data Register (MDR)

Question 10

MAR

Answer 10

Memory Address Register - Stores the address of current instruction being executed

Question 11

MDR

Answer 11

Memory Data Register - Holds the data found at the address held in the MAR

Question 12

FDE cycle

Answer 12

Fetch, Decode, Execute
FETCH instruction from main memory
DECODE instruction
EXECUTE instruction

Question 13

Purpose of buses

Answer 13

Allows components to transfer data between each other

Question 14

Types of buses

Answer 14

-Address
-Data
-Control

Question 15

Address bus

Answer 15

-Unidirectional
-Carries addresses from MAR to main memory

Question 16

Data bus

Answer 16

-Bidirectional
-Carries data from MDR to main memory and vice versa

Question 17

Control bus

Answer 17

-Bidirectional
-Carries commands from Control Unit to main memory and vice versa

Question 18

Instruction sets

Answer 18

List of machine-specific instructions that can be recognised by CPU. It is machine code.

Question 19

Embedded system

Answer 19

Single processor with RAM, ROM, and CPU

Question 20

Cache

Answer 20

Small, expensive memory in CPU
Faster to access than main memory

Question 21

3 Levels of cache

Answer 21

Level 1 - Small, close to processor
Level 2 - Medium, fairly close to processor, fairly fast
Level 3 - Relatively large, close to RAM

Question 22

CPU performance factors (3)

Answer 22

-Clock speed
-File type and size
-Processor cores

Question 23

Dual-core processors

Answer 23

-Two processors in same circuit linked together
-Twice the power
-Not twice as fast as software may not be able to take full advantage of both

Question 24

Clock speed

Answer 24

1 cycle per second = 1 instruction carried out per second = 1 Hz

Question 25

Input devices

Answer 25

Devices that allow you to pass information from the outside world to a computer system

Question 26

Output devices

Answer 26

Devices that take stored data in digital form to another form that humans can process (e.g. sound, sight)

Question 27

Laser printer vs Inkjet printer

Answer 27

Laser printer: -High quality -Fast -Accurate -Used in offices or schools Inkjet printers: -Small-scale -Personal use

Question 28

LCD screen vs LED screen

Answer 28

LCD screen: -Tiny liquid crystals form a matrix -Affected by changes in electrical fields -TVs, monitors, laptops LED screen: -Light emitting diodes prouce bright images -Large displays

Question 29

LCD projector vs LED projector

Answer 29

LCD projector: -3 mirror filters separate images into RGB wavelengths -Images passed through prism and recombined -Present through lens LED projector: -Micro-mirrors places on microchip with projector -White light shone through rotating colour filter to produce image

Question 30

Touch screen types

Answer 30

-Infrared -Resistive -Capacitive

Question 31

Infrared touch screen

Answer 31

-LEDs shine light across screen, forming matrix -Beams interrupted when screen touched -Large-scale displays, medical equipment

Question 32

Resistive touch screen

Answer 32

-2 conductive layers separated by insulating layer -Top layer is flexible -When pressed, the layers make contact -ATMs, medical equipment

Question 33

Capacitive touch screen

Answer 33

-Protective layer, transparent conductive layer, glass substrate -Touching screen changes electrostatic field of conductive layer -Tablets, phones

Question 34

Sensors

Answer 34

Input devices which measure the physical properties of their environment

Question 35

Analogue to digital converter

Answer 35

Converts real world values into digital values

Question 36

14 types of sensors

Answer 36

-Acoustic -Accelerometer -Level -Humidity -Infrared -Moisture -pH -Gas -Flow -Humidity -Magnetic field -Light -Proximity -Pressure

Question 37

Primary storage

Answer 37

Can be directly accessed by CPU Uses non-moving parts -ROM -RAM

Question 38

Secondary storage

Answer 38

Stores data for long-term use Cannot be directly accessed by CPU Uses moving parts so it is slower to access -Data has to be loaded from it to primary storage to be processed -Larger storage capacity than primary storage -Hard-disk drives (HDD) -Solid-state drives (SSD) -Optical storage (DVDs, Blu-ray disks)

Question 39

RAM

Answer 39

-Primary storage -Can be written to or read from -Volatile (when device is turned off, contents are all lost and deleted) -Stores data, applications, and OS

Question 40

ROM

Answer 40

-Primary storage -Contents cannot be changed -Contents can only be read by a system -Non-volatile -Stores initial instructions for computer to follow when it is turned on (How to load OS so it can boot up)

Question 41

Hard-disk drive (HDD)

Answer 41

-Have platters that are usually made of glass or aluminium -Platters are coated with a thin layer of magnetic material. Magnetised to represent binary data -Read/write head is mounted on an actuator -The head can change or detect the orientation of the magnetic material to read or write data -Head constantly moves - slow -Actuator moves the head to desired track on platter -Tracks are concentric circles on platter surface -Tracks are further divided into sectors -Sectors are the smallest storage unit on the disk

Question 42

Solid-state drive (SSD)

Answer 42

-Uses flash memory to store and retrieve data -Faster and lighter than HDDs -Thin in size -Do not last as long as HDDs because of charge leak -Work by moving electrons within NAND and NOR chips -Data is stored in binary in millions of tiny transistors -Place where transistors meet is called a junction -A floating gate and a control gate are found at junctions -Transistors are separated by an insulator -> so electron keeps its charge -Floating gate has value of 1 when electrons charged and 0 when not -Voltage applied to control gate so electrons from source are attracted to it -Electrons get trapped in floating gate -> allows us to have control over bit value stored in each intersection -Charge can leak away

Question 43

Optical disks

Answer 43

-CDs -DVDs -Blu-ray disks -Lasers used to read and write data to and from disk surfaces -Disk surfaces have a single spiral track that goes from the centre to the edge -When disk spins, optical head moves to where laser contacts with disk surface. Laser then follows the track from centre outwards -The track has pits and lands. Pits show there is no data to be read. Lands reflect data back to reader

Question 44

Physical memory vs Virtual memory

Answer 44

Physical memory: RAM Virtual memory: RAM + swap space on HDD/SSD

Question 45

Virtual memory

Answer 45

-Uses paging to store and retrieve date from SSD/HDD to RAM -A page is a fixed length consecutive block of data

Question 46

Advantages and disadvantages of virtual memory (2 each)

Answer 46

Pros: -Programs that are larger that physical memory can still be executed -Reduces need to buy expensive RAM Cons: -Disk thrashing can occur (high read/write rate causes processing to not take place, which stops the system) -Slow compared to using only RAM

Question 47

Cloud storage

Answer 47

Storing data in remote servers -Same data is stored in multiple servers in case of server maintenance, repair, or failure -Servers owned by a hosting company and are in many different locations

Question 48

Pros of cloud storage (Max. 4)

Answer 48

-Data can be accessed anywhere with an Internet connection -Can be accessed on different machines -No need for HDD/SSD -Unlimited amount of storage, for a price

Question 49

Cons of cloud storage (Max. 5)

Answer 49

-Internet connection needed to access -Slow Internet could cause problems with accessing -Cloud storage company could have failure resulting in data being lost -Costs can be high -Possible high cost of data transfer with ISP

Question 50

Network Interface Card (NIC)

Answer 50

Any device which allows access to a network (Ethernet, Bluetooth, Internet) Every NIC has a MAC address

Question 51

MAC address

Answer 51

Media Access Control -Made up of hexadecimal characters -First 6 represent OID (organisation that created the device) -Last 6 represent NICS (device's unique serial number) -Allows data packets to be sent to and from a network

Question 52

IP address

Answer 52

Internet Protocol address -Given to device by router on the network. Used as an identifier for a device -Allows device to send and receive data packets from a network -Can be static or dynamic (permanently assigned or changing with time) Two types: IPv4 - 32 bits, lower number of addresses that can be used at a time IPv6 - 128 bits, removes risk of IP address collisions, more efficient packet routes, built in authentication checks

Question 53

MAC address vs IP address

Answer 53

MAC address: -Physical address on a network -Assigned by manufacturer -Unique -Uses 48 bits IP address: -Global address on a network -Assigned by router -Not always unique -Uses either 32 bits (IPv4) or 128 bits (IPv6)

Question 54

Routers

Answer 54

-Sends data to a specific destination on a network -Allows data packets to be routed between different networks 1) Takes data transmitted in one format from a network 2) Converts data to another format understood by another network