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What is Primary storage?
Primary storage (also known as main memory) holds data, programs and instructions that are currently in use.
What is Random Access Memory?
Stores data currently in use. Volatile storage meaning data is deleted when power is lost
What is Read Only Memory(ROM)?
Stores the boot up sequence/ instructions. Can not be edited. Non volatile.
What is Virtual memory?
When RAM is full a portion of the HDD (hard drive) is allocated to act like RAM. Data is moved between Virtual memory and RAM when needed by the CPU.
What is Secondary Storage?
Includes hard drive/ solid state drive. This is for permanent storage e.g. where you store data so that it can be retrieved when the computer is switched on again.
What is Optical Storage?
Data is read using a laser. Data is stored by making indents on a disc to represent the 1’s or 0’s. Includes CD, DVD, CD-R, CD-RW etc.
What is Magnetic Storage?
Data is stored on a series of silver platters by magnetising the platter to represent the 1 or 0. Read by a needle that moves over the platter as it spins.
What is Solid state storage?
No moving parts. Stores data by holding electric currents in gates. Very fast read/write speeds.
What is Binary?
Storing data using 1’s and 0’s to represent on/ off of the switches inside a computer.
What are Forms of data storage?
A single 1 or 0 is a bit (this is the smallest form of storage in a computer).
4 bits = a nibble.
8 bits = 1 byte.
1000 bytes = 1 Kilobyte.
1000 Kb = 1 Megabyte
then it follows same pattern to Gigabyte, Terabyte, Petabyte.
What is Metadata?
Data about a file. E.g. for an image the height, width, resolution.
What is a Pixel?
Millions of “dots” make up an image by each displaying a different colour
What does the term ‘colour depth’ mean?
The range of colours that can be represented in each pixel |
What is the resolution of an image?
The number of pixels per inch of an image
What does the term ’Analogue’ mean?
How sound actually travels e.g. using analogue waves – however computers can only represent digital waves (1 or 0)
What is Amplitude?
The height of an analogue wave
What does the term ‘Sample’ mean?
Measurements of the amplitude of a wave – a binary value is stored to represent this
What does the term‘Sample rate’ mean?
The number of samples taken within a second (measured in Hertz). The higher the sample rate the better the quality of sound/ closer to the original (however also the bigger the file size)
What does Bit depth mean?
The number of bits of data stored per sample.
The more bits of data the more detail stored about the sample. However also the bigger the file size.
What does duration mean?
The length of the sound
What is the equation for Sound File size ?
sample rate x duration (s) x bit depth
What is the equation for Image File Size?
colour depth x image height (pixels) x image width (pixels)
What is the equation for Text File Size?
bits per character x number of characters
What is Hexadecimal?
Each hex value represents 1 nibble of data so can store 16 different values. These are 0 through to F
What is Denary?
The number system we use to count e.g. 1,2,3,4,5,6 |
What is a Character set?
A collection of characters and the bit-patterns used to represent them on a computer
What is ASCII
Stores characters using 1 byte of data per character – therefore can represent a maximum of 256 characters. A is 65 so B is 66, C is 67 etc. a is 97 so b is 98 etc
What is Unicode?
Uses more bits to store each character (up to 4 bytes per character). Therefore can represent a lot more characters such as emojis or characters from other languages. However file size will be bigger.
What is Compression?
Reducing the size of the file. Makes it smaller to store, smaller to download, smaller to transfer on a network.
What is Lossy Compression?
Detail is removed. The original can never be recreated (e.g. reducing colour depth or resolution on an image)
What is Lossless compression?
Original can be recreated. Compressed by spotting patterns e.g. 500 blue pixels in a row.
