Hardware Flashcards

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1
Q

CPU

A

Central Processing Unit - Responsible for computer’s processing

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2
Q

ALU

A

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

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3
Q

CU

A

Control Unit - Coordinates CPU activities

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4
Q

General Purpose Register

A

Small amounts of memory in CPU that hold data

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5
Q

Accumulator

A

Temporarily stores results of arithmetic + logic operations

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6
Q

PC

A

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

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7
Q

Von Neumann architecture

A

Storing program and data in the same memory

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8
Q

CIR

A

Current Instruction Register - Stores current instruction to be executed

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9
Q

Memory Registers

A

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

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10
Q

MAR

A

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

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11
Q

MDR

A

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

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12
Q

FDE cycle

A

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

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13
Q

Purpose of buses

A

Allows components to transfer data between each other

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14
Q

Types of buses

A

-Address
-Data
-Control

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15
Q

Address bus

A

-Unidirectional
-Carries addresses from MAR to main memory

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16
Q

Data bus

A

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

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17
Q

Control bus

A

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

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18
Q

Instruction sets

A

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

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19
Q

Embedded system

A

Single processor with RAM, ROM, and CPU

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20
Q

Cache

A

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

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21
Q

3 Levels of cache

A

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

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22
Q

CPU performance factors (3)

A

-Clock speed
-File type and size
-Processor cores

23
Q

Dual-core processors

A

-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

24
Q

Clock speed

A

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

25
Q

Input devices

A

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

26
Q

Output devices

A

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

27
Q

Laser printer vs Inkjet printer

A

Laser printer:
-High quality
-Fast
-Accurate
-Used in offices or schools

Inkjet printers:
-Small-scale
-Personal use

28
Q

LCD screen vs LED screen

A

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

29
Q

LCD projector vs LED projector

A

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

30
Q

Touch screen types

A

-Infrared
-Resistive
-Capacitive

31
Q

Infrared touch screen

A

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

32
Q

Resistive touch screen

A

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

33
Q

Capacitive touch screen

A

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

34
Q

Sensors

A

Input devices which measure the physical properties of their environment

35
Q

Analogue to digital converter

A

Converts real world values into digital values

36
Q

14 types of sensors

A

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

37
Q

Primary storage

A

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

38
Q

Secondary storage

A

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)

39
Q

RAM

A

-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

40
Q

ROM

A

-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)

41
Q

Hard-disk drive (HDD)

A

-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

42
Q

Solid-state drive (SSD)

A

-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

43
Q

Optical disks

A

-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

44
Q

Physical memory vs Virtual memory

A

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

45
Q

Virtual memory

A

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

46
Q

Advantages and disadvantages of virtual memory (2 each)

A

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

47
Q

Cloud storage

A

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

48
Q

Pros of cloud storage (Max. 4)

A

-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

49
Q

Cons of cloud storage (Max. 5)

A

-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

50
Q

Network Interface Card (NIC)

A

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

51
Q

MAC address

A

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

52
Q

IP address

A

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

53
Q

MAC address vs IP address

A

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)

54
Q

Routers

A

-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