3 Hardware Flashcards
What is the role of the CPU
An integrated circuit which accepts data input into the computer and processes it into information ready for output.
What does a CPU consist of? (3)
control unit
Arithmetic and logic unit
reigsters and buses
What is the role of the ALU?
responsible for carrying out mathematical calculations or logical operations
What is the role of the control unit? (2)
oversees the overall operation of the CPU
Includes initiating each step of the fetch decode execute cycle and managing the ALU
What is a register
small area of storage found within the CPU
Why are registers extremely fast to access
located directly within the CPU
what is the purpose of the current instruction register
CIR stores the current instruction being decoded and executed
what is the purpose of the accumaltor
used when carrying out ALU calculations
temporarily stores data during calculations
What is the purpose the memory address reigster
MAR stores the address of the RAM currently being read from or written to
What is the purpose of Memory Data Register
Register used to temporarily store data that will be written to RAM or data that has just been read from RAM.
What is the function of the program counter
PC stores the address where the next instruction to be read can be found
Define buses
a connection between major components in a computer that can carry data, addresses, or control signals
Describe the address bus (2)
carries addresses throughout the CPU
unidirectional (bits can travel one direction only)
Describe the data bus (2)
bidirectional (allows data to be sent in both ways along the bus)
Connects CPU with RAM and input devices with output devices
What are the three types of buses
address bus
data bus
control bus
Describe the control bus
bidirectional
carries signals from the Control Unit to all other computer components
Explain the fetch decode execute cycle (7)
The PC contains address of memory location of the next instruction which is to be fetched
address copied from PC to MAR via address bus
Contents in RAM address stored in MAR copied temporarily to MDR
Contents of MDR copied to CIR
Value of PC incremented by 1 so that it now points to the next instruction which is to be fetched
CU decodes instruction in CIR
instruction sent to ALU to be executed
What are the three main factors that affect the performance of a CPU
clock speed
cache
core
What is clock speed (2)
determines the number of cycles a cpu can perform each second
higher clock speed generates more heat and uses more energy
Describe the core (2)
processor within the CPU
The idea of using more core alleviates the need to increase clock speed
Describe the cache (2)
extremely fast memory located within the CPU
used to temporary store copies of the data in the most commonly accessed RAM locations
Define instruction set
Listof instructions that a CPU can process
when instructions are in binary it is known as machine code
Define embedded system
computer system that performs a dedicated function inside a device or appliance
Examples of where embedded systems can be found
Entertainment systems in cars
Domestic appliances, such as washing machines
Security systems, such as automatic lighting and alarms.
What are general purpose computers
A computer system designed to perform unlimited different functions.
Benefits of embedded systems (3)
small, easy to fit into devices
compared to other systems, relatively low cost to make
consumes very little power
Drawbacks of embedded systems (2)
any device that can be accessed over the internet is open to hackers, viruses etc
troubleshooting faults in the device becomes a specialist task
Define input devices
used to enter data into a computer for processing
Describe the process when barcode is scanned (4)
shine a light at a barcode
light is reflected off the barcode (white reflects light back, black absorbs and reflects less)
reflected light is read by microprocessor
a pattern is created and is converted to digital data
Describe the QR code (2)
Consists of square black and white patterns, representing a small number of text characters
As more and more data is added, structure of QR code becomes more complex
Advantages of QR code compared to traditional barcode (4)
can hold much more information
easy to transmit QR codes
possible to encrypt QR codes
easy to read (don’t need expensive laser or LED)
What happens when a photograph is taken by a digital camera? (3)
Light enters camera, falls onto sensor made up of millions of pixels
each pixel measures light intensity
microprocessor converts these values into digital data, representing colour values
What happens when a key is pressed (4)
there is a membrane or circuit board at the base of the keys
CPU determines which key has been pressed
CPU refers to an index file which identifies which character the key pressed represents
Each character on a keyboard has a corresponding ASCII value
What does a microphone do? (2)
vibrations caused by soundwaves cause a coil to move around a magnet, resulting in electromagnetic field changes
Tiny charges converted by microprocessor and ADC into digital representation of sound
What are the 3 types of touchscreens (3)
Resistive touchscreens
Capacitive touchscreens
infra red touch screens
What is resistive touch screen (3)
uses two very thin metal sheets over the screen
when pressure applied, metal sheet make contact, completing electrical circuit
this can be used to detect where the user has pressed
What is capacitive touch screens (3)
uses transparent layer over the screen
layer is sensitive to static electrical charge in human body
when user touches screen, charge detected, location of touch detected
What is infra-red touch screen (3)
creates a grid of infra-red light over the screen
when user touches screen, light is broken
this can be used to detect location of touch
How do 2D scanners work? (1)
shines bright line across a document to measure the levels of reflected light and create digital version of it
Describe 3D scanners (1)
shines a laser over the surface of an object to record its geometry and dimensions and create a digital model of it.
Why is a microphone required (2)
capture any real world sound and store it as digital data
digital sounds can then be modified
How does a optical mouse work? (2)
uses red LED and sensor to determine the movement of mouse relative to the surface beneath
microprocessor analyses speed and distance of the movement and replicates it on the screen via virtual cursor
Advantages of using an opitcal mouse (2)
no moving parts (more reliable)
no need for special surfaces (eg: a mouse mat)
What are 2D scanners typically used for (2)
reading passport at airports
creating digital versions of documents and photographs
What are 3D scanners typically used for (2)
Creating 3D models
dentistry, product development, research etc
What does an actuator do? (2)
carries out some sort of a physical movement
often used with motor to translate digital signal into real world physical movement
What does a digital light processing (DLP) projector do?
use thousands of tiny mirrors to reflect a digital image from a computer onto a screen.
Advantages of DLP projectors over LCD projectors (3)
smoother video
better suited to dusty or smokey atmospheres
portable
What does Liquid crystal display (LCD) projectors do?
create an image by projecting light in three colours: red, green and blue. These colours are combined to form a final image on the projector screen.
Advantages of LCD projectors over DLP projectors (3)
sharper image
better colour reproduction
less expensive
What does an inkjet printer do?
force tiny droplets of liquid ink through very fine nozzles onto a sheet of paper to replicate a digital document or iamge
What does a laser printer do?
use a laser to apply a static charge to areas on the paper.
Toner (a powdered ink) is then attracted to the static charge and sticks to the paper in these areas, forming an image.
What does LCD screen do? (3)
work by sandwiching crystals between two sheets of glass.
A white back light illuminates the screen from behind.
When an electrical current is applied to the crystals in individual pixels, light is passed through and an image forms.
What does LED screen do
use tiny LEDs to produce a bright image almost instantly without the need for any backlighting
advantages of LED screens over LCD screens (2)
Better image quality
no need for additional backlighting
What does a speaker do?
A speaker produces output in the form of sound, by converting electrical signals into vibrations.
What does a 3D printer do?
deposit layers of materials on top of each other to build 3D object
What is 3D printing often used for (3)
inexpensive prosthetics
personalised items
rapid prototyping
What role does Computer Aided Design (CAD) have in 3D printing
allows us to produce real world models of virtual objects
Define a sensor
A type of input device which measures an aspect of the environment around it
What is an acoustic sensor + applications
An acoustic sensor detects sound.
One application of an acoustic sensor would be a burglar alarm, which could be used to detect a break-in.
What is an accelerometer sensor + applications
An accelerometer measures acceleration force
Cars with stability control systems also use accelerometers to measure the car’s situation.
What is an flow sensor
Flow sensors measure the flow speed of liquids or gases in pipes.
What is an gas sensor + applications
Gas sensors can detect the presence of different gases.
a gas sensor may be used to detect the presence of toxic gases in a chemical manufacturing plant.
What is an Humidity sensor + applications
A humidity sensor detects water vapour in the air.
a greenhouse might use a humidity sensor to help a computer determine if the environment is correct for the plants growing there.
What is an infra-red sensor + applications
An infra-red (IR) sensor is a type of light sensor that detects invisible infra-red light.
an automatic door system might use an infra-red sensor to detect a person walking in front of the door.
How to answer sensor question (7)
1st mark – naming the sensor
eg: temperature sensor in air conditioner
2nd mark – Signal from the sensor is converted from analogue to digital by the ADC
3rd mark – Microprocessor compares digital value with stored value
4th mark- If its within a range, nothing happens
eg: air conditioner is set at 30 degrees and the room temperature is 30 degrees
5th mark – If its outside the range, a signal is sent to the actuator
6th mark- Does something (according to question)
7th mark- Operates in a continuous loop
What are the two types of storage in a computer storage (2)
primary storage
secondary storage
Define primary storage
storage that is accessed directly by the CPU
What are the two types of primary storage
RAM
ROM
Describe Random Access Memory (RAM) (4)
used for temporary storage of programs and data that are currently being used
Extremely fast to access
volatile (loses its contents when the power is removed)
Read and Write
Describe Read Only Memory (ROM) (3)
Read only
contains bootup instructions
non-volatile (data retained even after computer turned off)
Define + describe secondary storage (3)
type of storage that is not directly accessed by the CPU
non-volatile (permanently stores all of users’ data and programs)
larger capacities than primary storge
What are the 3 types of secondary storages (3)
magnetic storage
Optical storage
solid-state storage
Common example of magnetic storage
Hard disk drive
How does a magnetic hard disk drive work? (3)
inside a hard disk are multiple disks called platters, which spin constantly when the computer is running.
A read/write arm moves in and out across the disk surface,
an electromagnet on the read/write head is used to read and write the data on the disk.
How does an optical storage device work?
An arm moves the laser across the surface of the disk
The laser used to read the data from the pits and lands
When the laser light hits the point where the pit changes into a land or vice versa the light scatters and is not reflected back as well. This is captured by a sensor and can be interpreted as a change in the binary value
Examples of optical storage devices (3)
CDs
DVDs
Blu-rays
How does an SSD store data (6)
uses NAND/NOR technology/flip-flops
stores data by flashing it onto chips
controls flow of electrons using
transistors
electric current reaches control gate
current flows through to floating gate to be stored
when data is stored transistor is converted from 1 to 0
Define virutal memory
A system that allows a computer’s operating system to use secondary storage as though it were RAM.
What is paging out in virtual memory
When more RAM is needed than available, chunk of data (pages) moved from RAM to secondary storage, freeing up space
What is paging in virtual memory
When data needed again, the page must first be copied back from secondary storage to RAM
Define local storage
Storage devices which are directly connected to a computer system, such as a hard disk or a flash drive. The opposite of cloud storage.
Explain how cloud storage works (3)
uses servers on the internet
When a user saves data, that data is sent across the internet to a server, where it is stored
When user requires the data again, a request is sent to the server to retrieve the data again
What may cloud storages be used for (3)
data backup
photo and video uploads
streaming services
where are the servers for cloud stroage stored?
located in huge data centres that house thousands of servers
Benefits of using cloud storage (3)
data can be accessed from any device anywhere in the world, if provided with internet access
no need for user to carry external storage with them
offers almost unlimited storage capacity
Drawbacks of using cloud storage (3)
if user has slow unstable internet connection, they might have problems accessing data
costs can be high if large storage is required
potential failure of the cloud storage company risks the loss of back-up data
Purpose of Network Interface Card
hardware device that is needed to connect a computer to a network
Where is the MAC address usually found in a computer? (physically)
Network interface card
Explain what is meant by a MAC address (4)
hardware identifier that uniquely identifies each device
48 bits long, written in hexadecimal
1st part = manufacture cdode
2nd part = device serial number
Define IP address (1)
unique address assigned to each computer on a network.
What are the two types of IP addresses that can be allocated by a network (2)
static IP address
dynamic IP address
Explain what is ment by a static IP address
given the same address every time it joins the network
Explain what is meant by a dynamic IP address
it is assigned any available address when it joins the network
What are the two types of IP addresses (2)
IPv4
IPv6
Difference between IPv4 and IPv6 (2)
IPv6 128 bits in size while IPv4 only 32 bits
IPv6 is replacing IPv4 because IPv4 is running out
Define router
a device that that enables data packets to be moved between different networks
roles of the router (4)
They allow devices to connect to a LAN
They can assign IP addresses to devices joining a local network
They connect a local network to the internet
They send data to the correct destination on a network
