Input Devices- It allows data such as text, images, video, or sounds to be input into a computer
system. Such examples include Mouse, keyboard, Scanner.
Output Devices- Devices which allow the computer system to output data towards it. Examples
include Monitors, Printers, or Speakers.
A Biometric device uses a human characteristic such as Iris or Fingerprint. People first need to put
this data onto a database. When one is put onto a scanner, it checks against the database to see if it
is a match, so access is permitted, if not then access is denied.
Advantages: Security is improved as biometrics cannot be shared, if a password is exposed the
system can’t be accessed without the biometric, scanners verify that a person is who they claim to
be, using a biometric device might be quicker and easier than entering a username and password,
they also cannot be forgotten unlike usernames and passwords.
Disadvantages: They are expensive to install and time must be taken to set the biometric data up
initially, unreliable as it can be affected with the environment (Dirty fingers won’t work), Disabled
users may not be able to use some features, privacy concerns.
Computer Components:
All computers have three parts:
Processor: Manage the functions of a computer system by processing data and instructions. Primary
processor is the CPU.
Motherboard: It is the main circuit board of the computer on which components such as the CPU
and ROM are connected. The motherboard has PCI slots for expansion cards and ports for external
devices.
PSU: Converts electricity from AC from the mains power supply to DC which the computer can use. It
is internal for desktops, whilst portable devices require an external charger.
Memory is split into two types:
Volatile storage is temporary (Data is lost whenever the power is turned off)
Non-Volatile storage saves the data even when not being powered, so it can be accessed when the
computer is next on and can be stored long-term.
Primary Storage
RAM is volatile storage that stores all programs that are currently running. It also stores parts of the
OS to be accessed by the CPU. It is made up of a large number of storage locations, each of which
can be identified by a unique address.
,ROM is non-volatile storage that cannot be changed. It stores the boot program/BIOS for when the
computer is switched on. The BIOS then loads up the OS to take over managing the computer.
Cache Memory is volatile storage that stores data that is frequently accessed. It is very quick to
access because it is closer to the CPU than other types of memory like RAM.
Secondary Storage:
Magnetic Storage:
An HDD is the most common form of magnetic storage. A read/write head moves nanometres above
the disk platter and uses the magnetic field of the platter to read or edit data. Hard disk drives can
also be external and connected through a USB port. There is also magnetic tape which has high
storage levels but must be accessed in order so is used for things like backups. Large capacity, and
cheap but it is not very portable and can be damaged easily.
Optical Storage:
Uses a laser to project beams of light on a spinning disc, allowing it to read data from a CD, DVD, or
Blu-Ray Disc. It is the slowest of the bunch. It has low capacity, is slow, and is fragile. But it is thin
and portable.
Solid State Storage:
There are no moving parts in SSD Storage. They have mostly replaced HDDs due to the fact they
have a higher read/write speed, quieter, and use less power. USB is an example of SSD Storage.
Memory cards are another example. They have the highest access speed, they are portable, and
durable. However, they are expensive.
Cloud Technology:
A recent innovation where companies would offer to store your data on large servers. Examples
include Google Drive and Dropbox. These companies are responsible for storage and upkeep of the
servers. It is very convenient as it allows people to work on a file at the same time and it can be
accessed from different devices. However, if the internet connection fails, or the servers are
attacked then the data can become inaccessible. It has large capacity, and is easily scalable to
individual needs. However, you always need an internet connection to access your data.
Storage Protocols:
SCSI (Small Computer System Interface): a protocol for attaching external devices to a computer
system such as a printer or hard drive.
,SAS (Serial Attached SCSI): This is an improved version of SCSI that enables more external devices to
be connected at the same time to a computer system (Up to 128).
Expansion Cards:
Graphics Card: Processes graphical data and converts it into a displayable output onto the monitor
Network Interface Card: Allows computers to connect to networks and enables them to transfer
data to other computers.
Fibre Channel Card: Transfers data between servers on a network. Has quick transfer speeds and is
primarily used on servers in large data centres.
Sound Card: Converts analogue sound waves into digital data (Binary) (Using a microphone) and vice
versa (Speaker).
Storage Controller Card: Required for the computer to manage and use any attached storage
devices.
Embedded Systems: When a smaller computer system is installed within a larger device, such as a
washing machine, traffic light, or car. Embedded systems have a dedicated purpose and often run in
real time. The IoT Internet of Things describes a global network of connected objects that were
previously dumb, such as smart bulbs, smart plugs, and thermostats.
Mainframe: Large and very powerful computers that are reliable. Used to process large amounts of
data and can be used to solve scientific and engineering problems that require complex calculations
with large datasets (e.g. Weather forecasting or scientific simulations). They are reliable and secure
because of their large backup capabilities. They are very expensive and require teams of experts to
oversee them, and so are used only by organisations that need to process very large amounts of data
quickly, such as banks and airlines.
Quantum: Still in development and experimental phases. They work with quantum bits (Qubits),
which unlike binary, are not limited to just two states. They represent atomic particles, which can be
in several different states at the same time. It would potentially be able to process data and perform
calculations millions of times faster than currently available computers.
Copper Cables- Cheap form of wired internet connection that may be poorly insulated and therefore
susceptible to electromagnetic interference. More likely to suffer from network distortion. Malleable
and less likely to break than other cables such as fibre optic. They also have a lower bandwidth and
can therefore not transmit as much data at once/
Fibre Cables- They are a very fast, but expensive type of wired internet connection. Signals are
transmitted as waves of light through a glass tube. Because of this they are not affected by
electromagnetic interference and suffer less network distortion. They also have a higher bandwidth
and can transfer more data at once, but are more fragile.
, Bluetooth- A temporary and short range communication between devices within a limit of ten
metres. Bluetooth can be used to transfer audio files or images from one smartphone to another.
The close proximity is a disadvantage, but no other hardware is required for the connection.
Infrared- They have been largely replaced by Bluetooth or Wi-Fi connections because infrared
requires devices to be in direct line of sight. They are still used by some devices such as remote
controls to transmit signals to a TV but only works across a short distance.
Microwave- Use radio waves to send signals across a large area via microwave towers. Can transmit
a large amount of data but antennas need to be in the line of sight of each other with no
obstructions. They are also affected by bad weather, leading to higher chances of network
distortion.
Laser- Although not common, laser connections can send data between devices that are in the line
of sight of each other as long as there are no barriers. Laser connections can transmit data up to 2km
but bad weather severely affects the transmission rate. They can be used in space as there are fewer
barriers between the satellites.
Satellite networks use point-to-point multipoint communication by using satellites above the Earth’s
atmosphere that receive a transmission and rebroadcast them back to Earth. Because of the
distance between the communication device and the satellite, there is a delay between data
transmission and it being received (This is called latency, and is the reason those news presenters
always pause when talked to!
GSM (Global System for Mobile Communications) is a technology for allowing mobile phones to
connect to a network for calls and text messages. Advances in mobile technology are classified by
generations such as 4G and 5G (The current generation). Each generation tends to be faster and
more secure than the last.
Comms Hardware:
Hub: Receives data packets from a connected device and transfers a copy to all connected nodes.
Switch: A switch receives data packets, processes them, and then transfers them onto the device
specifically listed in the destination address of the packet.
Modem: They are used to send data across the telephone network. As they can only transfer analog
signals, this means a modem is used to convert a computer’s digital data into an analog signal.
Another modem converts the signal back to a digital format at the receiving end.
Router: They are used to transfer data packets between networks. Data is sent from network to
network on the internet towards the destination address listed in the data packet. A router stores
the address of each computer on the network and uses routing tables to calculate the quickest and
shortest path.
