An input device can be used to input data into a computer, and an output device can be used to take out or display information from a computer.
Keyboard
Mouse
Speaker
Webcam
Printer
Monitor
Projector
Touch screen
Headset
Virtual reality headset
Optical Storage
Optical storage uses lasers to read and write data.
The lasers create small divots (called pits), and areas without pits are called lands.
A pit represents 0 and a fall represents one.
Data can be read by detecting whether light is reflected or scattered.
Compact discs are light, portable and thin for easy storage;
however, they are easily damaged and can only hold small amounts of data
DVDs can hold much more data than CDs, making them useful for videos and movies.
Blu-ray discs are capable of holding up to five times more data as a DVD making them suitable for high-resolution films.
Magnetic storage
This type of storage uses the two magnetic states to represent binary, polarised and unpolarised.
HDDs have large capacities (from 500GB — 5TB).
Magnetic discs rotate at high speeds while an actuating arm reads and writes from them.
Usually, multiple discs are layered on top of each other for extra capacity.
Despite this, HDDs are fragile, have many moving parts, and data can be overwritten by strong magnet fields.
Long stretches of magnetic tape are wound onto reels, and can be read from by tape readers.
Magnetic tape is very cheap and is used commonly for backups of important files;
however, data can be overwritten by strong magnetic fields.
Floppy discs are cheap, portable and light.
They were commonly used until flash drives were popularised.
The typical capacity of a floppy disc is about 1 MB; however, some can hold up to 200MB.
Flash storage
Flash storage is fast and compact.
Through the use of silicon semiconductors,
logic gates can be used to store an electrical charge in one of two states which represent binary.
Information is stored in blocks of bits, which are combined to form pages.
SSDs can store massive amounts of data ranging from 500GB — 20TB.
They are light and portable, as well as extremely durable.
SSDs also have fast read-write speeds.
The main disadvantage of SSDs is their cost, which is gradually decreasing as they become more common.
RAM and ROM
Random access memory (RAM) is volatile memory used to store data of processes which are currently running.
Read-only memory (ROM) is non-volatile memory used to store instructions like a computer's startup routine.
Virtual storage
Virtual storage refers to storing data remotely.
For example, cloud-based storage stores data on external servers.
The data can be retrieved from any device with an internet connection from anywhere, making this method convenient.
The speed of virtual storage depends on internet speeds and bandwidths, which are increasing over time.
However, cloud storage is typically expensive and is limited by a user's internet connection.