Input, Output and Storage Flashcards
input device
An input device is one which can be used to put data and information into a computer.
examples input device
Keyboard
Used to enter text into a computer
Webcam
A camera used by a computer to take photos and record videos
Magnetic stripe reader
Used to read data from magnetic stripes on cards like credit and debit cards
Barcode reader
Used in supermarket checkouts and access control systems to read information
from printed labels and cards
output device
Likewise, an output device is one which can be used to send information from the
computer.
examples output device
Speakers
Used to output sound from a computer
Printers
Used to output information from a computer onto paper
Projector
Used to project video content from a computer onto a screen
input output devices
A small number of devices can be categorised as both input and output devices. For
example, a touch screen outputs information in a visual way like a monitor, while acting as
a device for touch input.
use of storage
There are a variety of different methods of storing information, each of which is suited to a
particular type of information. Some devices are best for storing small quantities of
information, while others are suited to large capacity storage.
cds
CD stands for compact disc. They use optical technology to store small quantities of
information. Most commonly used for audio files, CDs can also be used to store text
and digital images. CDs are small, thin and light which makes them very portable.
optical storage
Optical devices are read from and written to
using lasers. Binary information is represented
by portions of the disc which either reflect or
scatter the incident laser light written in spiral
tracks on the disc’s surface.
The
portions which are recessed, called pits, scatter
light whereas the flat portions, called lands,
reflect light. Pits represent a 0 and lands
represent a 1.
disavantage cd
Their disadvantages include being easily damaged by scratches, their limited
storage capacity and relatively slow transfer speeds.
blu-ray
An advancement over DVDs, blu-ray discs have more than five times as much
storage than traditional DVDs, making them useful for storing high-resolution films.
dvd
DVD stands for digital versatile disc or digital video disc. Similar to CDs, DVDs are
also optical devices which have a higher storage capacity than CDs, making them
suited to storing digital videos which require more storage space than audio files or
photos.
varieties cd
Varieties of CD include CD-R
which can only be written to once, CD-RW which can be written to more than once
and CD-ROM which is written to during production and can then only be read from.
magnetic sotrage
Devices which store information magnetically represent binary information using two
magnetic states: polarised and unpolarised. If a portion of magnetic material is polarised,
all magnetic poles align and can be read by a read/write head passing over the region. If
an area is not polarised, magnetic poles are randomly scattered and produce a different
reading on a read/write head. These two states can represent 1 and 0 , allowing any
information to be represented in binary form.
hard disk drives
Sometimes abbreviated to HDD, hard disk drives typically have high capacities of
between 500GB and 5TB. They work by rotating magnetic platters at high speeds
under a read/write head on an actuating arm. The combination of the arm and
rotating platter allows the read/write head to access any part of the platter. Most
HDDs will have multiple platters stacked on top of each other to maximise storage
capacity.
magnetic tape
First used to record computer data in the 1950s, magnetic tape was a popular
storage medium right through to the 1980s. Wound onto reels, long stretches of
tape were passed through readers which would check the polarity of the tape and
read off a binary value. Tape was a bulky way to store data, and although
improvements were made by reducing the width of the tape and writing in diagonal
lines as opposed to horizontal tracks, the technology was superseded by more
modern technology like ROM cartridges.
flash storage
Flash storage is fast and compact. The technology makes
use of silicon semiconductors forming the logic gates NAND
and NOR to store electrical charge in one of two states: high
or low. These two states represent the binary values True
and False, which can be used to represent information.
Information is stored in blocks, which are combined to form pages.
disavantage hdds
Disadvantages of HDDs include their somewhat slow data transfer speeds and their
tendency to become damaged by movement. The combination of brittle platters and
moving parts results in a delicate device.
floppy disk
A floppy disk comprises a thin magnetic disk (which would have originally been
flexible, hence the name) enclosed in plastic to protect the disk from dust and dirt.
They were incredibly portable, thanks to their thin size and low weight, so became
popular for exchanging small amounts of data - in a similar way to how USB flash
drives are used today. Floppy disks had a typical storage capacity of 1MB although
some later versions boasted as much as 200MB.
ram vs flash mem
Although flash memory is similar to RAM, the two differ in that RAM is volatile (loses its
content with loss of power) while flash memory retains its information.
