Topic 2 - Memory and storage Flashcards
(23 cards)
What are all the Primary storage and what do they do ?
RAM - Volatile, Holds open programs and data.
Stands for Random Access memory it can be changed.
ROM - Non volatile, Contains the program that runs when the computer boots (BIOS).
This program loads the OS from storage into RAM.
ROM is read only memory so can’t be changed.
What is secondary storage?
Large, non-volatile, long term storage for programs and data.
What is Virtual Memory?
When RAM is full, part of the secondary storage may be used as virtual memory.
Virtual memory is much slower than RAM therefore will slow down your computer.
What are the three main types of secondary storage and give one example of each.
Magnetic - Hard disk drive.
Optical - DVD
Solid State - Solid State Drive (SSD)
How does Magnetic storage work and what are the pros/cons?
Uses two levels of magnetic polarity.
Contains a spinning disk.
One represents binary 1
other represents binary 0.
These are reliable and come with large capacities.
Cheap per GB.
But not very durable and are noisy
How does Optical storage work and what are the pros and cons?
Uses light and different reflections of light to represent binary 1 and binary 0.
Contains a spinning disk
They are portable and reliable.
Not durable and have a low capacity per disc.
Cheap per GB.
How does solid state storage work and what are the pros/cons?
It is a big chunk of electronic circuitry lots of logic gates nothing is moving.
Have fast read and write speeds and are durable.
They are expensive per GB.
What are the two key rules in binary addition?
1+1 = 0 carry the 1.
1+1+1 = 1 carry the 1
In a left binary shift what happens to the number?
A left shift the number 1 doubles.
A right shift halfs number
What is an overflow error?
Where your result takes more storage space than possible.
Define character set.
A character set is a group of character codes.
ASCII - 8 bit per character only room for 256 characters.
Unicode can represent thousands of characters.
Define resolution.
Number of pixels.
Define colour depth.
Number of bits per pixel.
What is metadata.
Data about the image such as height, width, colour depth, file type etc.
How is analogue sound converted into digital sound.
Samples of the amplitude are taken at regular time intervals. More sample = higher quality.
Then each sample is converted into and stored as binary.
What is sample rate and what is it measured in?
Sample rate = number of samples per second in Hz.
What is bit depth?
Number of bits per sample.
What does compression do?
Reduce file size so takes up less storage space and shorter transmission times.
What is Lossy compression?
LOSSY deletes parts of the file permanently reducing quality.
What is LOSSLESS compresion?
LOSSLESS represents the file in a more efficient way does not remove important information.
Equation for Sound file size =
Sample rate * duration
Equation for image file size =
Colour depth * image height * image width
Equation for text file size?
Bits per character * number of characters
