1.1.3 - Input, Output and Storage Flashcards
What is an input device?
One which can be used to put data and info into a computer.
What is an output device?
An output device is one which can be used to send information from the computer.
Name 4 examples of input devices?
Keyboard
Webcam
Magnetic stripe reader
Barcode reader
Name 3 examples of output devices?
Speakers
Printers
Projector
Give an example of a double input/output device?
Touch screen
What should you consider when purchasing an input device?
Speed
Accuracy
Cost
Relevance
What are optical devices?
Optical devices are read from and written to
using lasers shone into spiral tracks on the disc surface.
How does the surface of an optical disc represent data?
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.
What is a CD?
This is a compact disc which uses 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.
Pros and cons of CD.
Small, thin and light making them very portable.
Easily scratched, limited storage capacity and slow data transfer speeds.
What is a DVD?
Digital video discs are 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.
What is a Blu-Ray?
Blu-rays have e more than five times as much
storage than traditional DVDs, making them useful for storing high-resolution films
How does magnetic storage work?
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.
How does an HDD work?
HDDs 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.
Pros and cons of HDDs.
High capacities (500gb-5tb) Slow data transfer speeds and damaged by movement because of their moving parts and brittle platters.
How does magnetic tape work?
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.
What is the issue with magnetic tape?
It was a bulky way to store data, and data is read in sequentially meaning it is hard to locate data.
What is a floppy disk?
It is a thin magnetic disk (which would have originally been
flexible, hence the name) enclosed in plastic to protect the disk from dust and dirt
Pros and cons of floppy disks.
Incredibly portable and cheap- but very small storage capacity(1-200mb) and data transfer speed, and low reliability.
How does flash storage work?
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.
Features of flash memory.
Flash memory can be erased and reprogrammed electronically, and is non-volatile,
meaning it stores its data even when power is lost.
Pros and cons of SSDs
Light and portable, no moving parts so resistant to damage. High data transfer rates.
However, high cost and limited lifespan (Every time a page is written to the voltage to write to it increases).
What is primary storage.
Storage used by the computer’s operating
system to run the computer. They store information like code instructions to execute and
files which are required by running programs.
What is RAM?
Random access memory is a type of fast main memory used to store data and
programs that the computer is currently using.
