Knowt
Unit 3.1 Computers and their Components
Aims
Know the difference between input and output devices and be able to identify a range of different devices.
Know the difference between memory and storage and be able to identify a range of different devices.
Know the difference between monitoring systems and control systems and the importance of feedback.
CPU - Central Processing Unit - processes data and controls what the computer does.
Input Devices
Hardware that allows you to pass information from the outside world into a computer system e.g. text/mouse clicks
Input Device | Description |
Keyboard | Enters text such as letters/numbers/punctuation. |
Mouse | Select options on the screen |
Touch Screen | Same as mouse but with the users fingers (aka hybrid device as it can input/output) |
Webcam | Enters live images - usually for video calls |
QR Reader | Reads data stored as an image - usually links to websites |
Biometric Reader | reads users biometrics e.g. fingerprint/voice/facial recognition |
Scanners | Converts documents from physical to digital form |
Sensor | Collects environment data e.g. noise/light/temperature and moisture |
Barcode Reader | Scan/read barcodes and converts it to a number which can be used to look up items in a database |
Games Controller | Inputs commands into a game e.g. direction/camera rotation etc. |
Microphone | Enters voice commands into a program, also used for voice/video calls and speech to text recognition software |
Graphics Tablet | Allows the creation of freehand drawings using a pen |
Output Devices
Hardware that displays processed data/ takes digital data and convert to another format that can be processed by humans i.e sound/images/vibrations
Output Device | Description |
Monitor | Displays graphical info on a screen, is what the users sees and allows interaction with the device |
Printer | Creates physical copies of digital documents |
Speaker | Outputs sounds e.g. music/sound effects |
Projector | Displays contents of a monitor onto a large screen/wall |
3D Printer | Creates 3D objects by layering materials |
Memory and Storage
DIFFERENT THINGS!!
Memory (think of human short term memory) | Storage (book) |
Provides very fast temporary storage for active data and programs whilst they are being processed by the CPU | Provides permanent storage of large quantities of data |
Direct contact with the CPU | No direct contact with the CPU |
Data isn’t saved when the power is switched off-volatile | Data is saved when the power is turned off-non volatile |
Secondary Storage Devices
Provide permanent storage of vast amounts of data:
Optical Disc Readers/Writers
Solid state (Flash) Drives
Magnetic Hard Drives
Optical Disc Reader/Writer
Contains tiny pits and lands ( too small to be seen)
Binary data is burnt into the pits and lands into a spiral track circulating outwards from the centre
Data is read by a laser beam passing over the pits and lands, where the light is reflected back to signal 0’s and 1’s
CD’s hold 700MB approx
DVD’s hold 4.7GB approx
Blu-Rays hold 25GB approx
Pros | Cons |
Individual disc’s are cheap (become expensive the more you need) | Can be easily damaged |
Portable | Small storage capacity |
slow read and write speeds |
Flash Drives (Solid State)
Use non-volatile flash memory to store data and are made up of microchips and switches
Data stored by changing the switch states on the microchip, state determines a 1 or 0.
Hard drives hold 1-4TB
Memory Sticks and SD Cards hold up to 128GB
Pros | Cons |
Very robust (no moving parts) | Very expensive |
High storage capacity | |
Very fast read and write speeds (no moving parts) | |
Very portable and lightweight |
Magnetic Hard Drives
Made up from a a platter which is a circular disk that can spin
Platter splits into circles called tracks which are then further divided into sectors.
Data is stored by magnetising the sectors which are read by disk heads mounted on mechanical arms
Pros | Cons |
Very cheap | Not very portable (heavy and built into computers) |
Offer high storage capacity | Easy to damage (lots of moving parts) |
Fast read and write speeds |
RAM and ROM - Primary Memory
REGISTERS AND CACHE ARE INTERNAL MEMORY!
RAM - Random Access Memory (GB)
Holds active programs and active data e.g. all programs/apps opened are held in RAM
Its very fast and allows CPU quicker access to the programs/data as opposed to secondary storage, therefore if RAM is boosted it improves performance as the more active data/programs can be held and avoids the computer from using Virtual memory when RAM is full which is a lot slower
Has Volatile Memory- if computer is turned off anything stored is lost
Contains buffers - temp storage areas where data is held whilst being transferred between two locations/processes - helps manage data flow between devices/components that may have different operating speeds e.g. Hard drive and RAM
Two types:
Static RAM (SRAM) - Faster than DRAM and doesnt need to be refreshed to maintain data however its more complicated, holds less data and is more expensive - mainly used for cache memory.
Dynamic RAM (DRAM) - Slower than SRAM and needs refreshing to maintain the charge in capacitors in order to hold the data however its simpler, cheaper and holds more data - mainly used as computers main memory
ROM - Read-Only Memory (MB)
Holds first instructions that will start the computer up (bootstrap) aka BIOS on motherboard
Rom tells CPU to do POST - Power on self test - sends signal to all components so CPU is aware of them - such as OS being on the hard drive
also can hold device specific settings
Non-Volatile memory - if computer turned off anything stored on ROM isn’t lost
Start up instructions are stored in ROM so that the instructions aren’t lost when the computer is turned off
Three types:
Programmable ROM (PROM) - Programmed once after manufacturing, once done data stored can’t be changed or erased so are used to store software not expected to change - PROM Writer uses electric currents to burn fuses in the matrix altering specific cells (only once as things cant be unburned) often mobiles and RFID tags
Erasable Programmable ROM (EPROM) - Can be programmed and erased multiple times and requires UV light to erase it, retains its power even when turned off and is often used for firmware where frequent changes are required. - floating gate transistors and capacitors and UV Light programmes it through quartz windows (pure glass)
Electrically Erasable Programmable ROM (EEPROM) - Can be erased and reprogrammed electrically, used in software where occasional modifications are needed i.e. changing configurations settings in electronic devices - NOR chips and electrical charges used to erase data, used in SSD’s
Embedded Systems
General purpose computer - often sits alone, completes many general tasks, different components that can be (dis)connected and the OS and software can be installed and easily updated.
“computer system with a dedicated function within a larger mechanical system”
Embedded system - built into another device/system, does limited number of specific tasks, fewer components that are purpose specific and integrated onto a single circuit and the OS is built in and is difficult to change/update e.g. cash machines/printers/vending machines/traffic lights etc.
Pros | Cons |
Easily mass produced, have everything required built onto a single circuit board so easy for machines to make | Difficult to upgrade - due to components on single circuit |
More reliable - fewer components to malfunction | Limited hardware, so limited tasks can be carried out |
Smaller in size - more portable | Difficulty trouble shooting - may need specialist when being fixed |
less expensive due to purpose specific components | |
low power consumption - ideal for battery operated devices |
Monitoring and Control Systems
Monitoring systems
Observes and gathers info about a system and reports the data back to a computer system only (doesn’t modify)
Sensors often used to collect info such as temperature, pressure changes, Infra-red (movement) and sound
Control systems
Monitor and modify the system to achieved desired outcome
Corrective action taken when certain conditions aren’t met e.g. water sprinklers in buildings to put out fires
Control systems use actuators - mechanical devices that convert input signals to physical action
Make use of feedback - Involves measuring system output being controlled and compare it to desired conditions, done continuously to ensure stable system e.g. turn on/off heating for specific temperature needs
Unit 3.1 Computers and their Components
Aims
Know the difference between input and output devices and be able to identify a range of different devices.
Know the difference between memory and storage and be able to identify a range of different devices.
Know the difference between monitoring systems and control systems and the importance of feedback.
CPU - Central Processing Unit - processes data and controls what the computer does.
Input Devices
Hardware that allows you to pass information from the outside world into a computer system e.g. text/mouse clicks
Input Device | Description |
Keyboard | Enters text such as letters/numbers/punctuation. |
Mouse | Select options on the screen |
Touch Screen | Same as mouse but with the users fingers (aka hybrid device as it can input/output) |
Webcam | Enters live images - usually for video calls |
QR Reader | Reads data stored as an image - usually links to websites |
Biometric Reader | reads users biometrics e.g. fingerprint/voice/facial recognition |
Scanners | Converts documents from physical to digital form |
Sensor | Collects environment data e.g. noise/light/temperature and moisture |
Barcode Reader | Scan/read barcodes and converts it to a number which can be used to look up items in a database |
Games Controller | Inputs commands into a game e.g. direction/camera rotation etc. |
Microphone | Enters voice commands into a program, also used for voice/video calls and speech to text recognition software |
Graphics Tablet | Allows the creation of freehand drawings using a pen |
Output Devices
Hardware that displays processed data/ takes digital data and convert to another format that can be processed by humans i.e sound/images/vibrations
Output Device | Description |
Monitor | Displays graphical info on a screen, is what the users sees and allows interaction with the device |
Printer | Creates physical copies of digital documents |
Speaker | Outputs sounds e.g. music/sound effects |
Projector | Displays contents of a monitor onto a large screen/wall |
3D Printer | Creates 3D objects by layering materials |
Memory and Storage
DIFFERENT THINGS!!
Memory (think of human short term memory) | Storage (book) |
Provides very fast temporary storage for active data and programs whilst they are being processed by the CPU | Provides permanent storage of large quantities of data |
Direct contact with the CPU | No direct contact with the CPU |
Data isn’t saved when the power is switched off-volatile | Data is saved when the power is turned off-non volatile |
Secondary Storage Devices
Provide permanent storage of vast amounts of data:
Optical Disc Readers/Writers
Solid state (Flash) Drives
Magnetic Hard Drives
Optical Disc Reader/Writer
Contains tiny pits and lands ( too small to be seen)
Binary data is burnt into the pits and lands into a spiral track circulating outwards from the centre
Data is read by a laser beam passing over the pits and lands, where the light is reflected back to signal 0’s and 1’s
CD’s hold 700MB approx
DVD’s hold 4.7GB approx
Blu-Rays hold 25GB approx
Pros | Cons |
Individual disc’s are cheap (become expensive the more you need) | Can be easily damaged |
Portable | Small storage capacity |
slow read and write speeds |
Flash Drives (Solid State)
Use non-volatile flash memory to store data and are made up of microchips and switches
Data stored by changing the switch states on the microchip, state determines a 1 or 0.
Hard drives hold 1-4TB
Memory Sticks and SD Cards hold up to 128GB
Pros | Cons |
Very robust (no moving parts) | Very expensive |
High storage capacity | |
Very fast read and write speeds (no moving parts) | |
Very portable and lightweight |
Magnetic Hard Drives
Made up from a a platter which is a circular disk that can spin
Platter splits into circles called tracks which are then further divided into sectors.
Data is stored by magnetising the sectors which are read by disk heads mounted on mechanical arms
Pros | Cons |
Very cheap | Not very portable (heavy and built into computers) |
Offer high storage capacity | Easy to damage (lots of moving parts) |
Fast read and write speeds |
RAM and ROM - Primary Memory
REGISTERS AND CACHE ARE INTERNAL MEMORY!
RAM - Random Access Memory (GB)
Holds active programs and active data e.g. all programs/apps opened are held in RAM
Its very fast and allows CPU quicker access to the programs/data as opposed to secondary storage, therefore if RAM is boosted it improves performance as the more active data/programs can be held and avoids the computer from using Virtual memory when RAM is full which is a lot slower
Has Volatile Memory- if computer is turned off anything stored is lost
Contains buffers - temp storage areas where data is held whilst being transferred between two locations/processes - helps manage data flow between devices/components that may have different operating speeds e.g. Hard drive and RAM
Two types:
Static RAM (SRAM) - Faster than DRAM and doesnt need to be refreshed to maintain data however its more complicated, holds less data and is more expensive - mainly used for cache memory.
Dynamic RAM (DRAM) - Slower than SRAM and needs refreshing to maintain the charge in capacitors in order to hold the data however its simpler, cheaper and holds more data - mainly used as computers main memory
ROM - Read-Only Memory (MB)
Holds first instructions that will start the computer up (bootstrap) aka BIOS on motherboard
Rom tells CPU to do POST - Power on self test - sends signal to all components so CPU is aware of them - such as OS being on the hard drive
also can hold device specific settings
Non-Volatile memory - if computer turned off anything stored on ROM isn’t lost
Start up instructions are stored in ROM so that the instructions aren’t lost when the computer is turned off
Three types:
Programmable ROM (PROM) - Programmed once after manufacturing, once done data stored can’t be changed or erased so are used to store software not expected to change - PROM Writer uses electric currents to burn fuses in the matrix altering specific cells (only once as things cant be unburned) often mobiles and RFID tags
Erasable Programmable ROM (EPROM) - Can be programmed and erased multiple times and requires UV light to erase it, retains its power even when turned off and is often used for firmware where frequent changes are required. - floating gate transistors and capacitors and UV Light programmes it through quartz windows (pure glass)
Electrically Erasable Programmable ROM (EEPROM) - Can be erased and reprogrammed electrically, used in software where occasional modifications are needed i.e. changing configurations settings in electronic devices - NOR chips and electrical charges used to erase data, used in SSD’s
Embedded Systems
General purpose computer - often sits alone, completes many general tasks, different components that can be (dis)connected and the OS and software can be installed and easily updated.
“computer system with a dedicated function within a larger mechanical system”
Embedded system - built into another device/system, does limited number of specific tasks, fewer components that are purpose specific and integrated onto a single circuit and the OS is built in and is difficult to change/update e.g. cash machines/printers/vending machines/traffic lights etc.
Pros | Cons |
Easily mass produced, have everything required built onto a single circuit board so easy for machines to make | Difficult to upgrade - due to components on single circuit |
More reliable - fewer components to malfunction | Limited hardware, so limited tasks can be carried out |
Smaller in size - more portable | Difficulty trouble shooting - may need specialist when being fixed |
less expensive due to purpose specific components | |
low power consumption - ideal for battery operated devices |
Monitoring and Control Systems
Monitoring systems
Observes and gathers info about a system and reports the data back to a computer system only (doesn’t modify)
Sensors often used to collect info such as temperature, pressure changes, Infra-red (movement) and sound
Control systems
Monitor and modify the system to achieved desired outcome
Corrective action taken when certain conditions aren’t met e.g. water sprinklers in buildings to put out fires
Control systems use actuators - mechanical devices that convert input signals to physical action
Make use of feedback - Involves measuring system output being controlled and compare it to desired conditions, done continuously to ensure stable system e.g. turn on/off heating for specific temperature needs
