Memory & Storage Flashcards
Describe the differences between Primary and Secondary storage
Primary is quick, easily accessed by the CPU and is referred to as main memory (includes RAM and ROM). Secondary is slower however has a larger capacity and long-term
Describe the difference between volatile and non-volatile storage
Volatile storage is temporary, which means data is lost when the power is turned off. Non-volatile storage saves data
Why do computers need primary storage
Program instructions and data must be copied from the hard drive into RAM by the CPU because primary storage access speeds are much faster than secondary storage devices
What is RAM and what information is stored in it
Random Access Memory is volatile storage which stores all the programs which are currently running. RAM is made up of a large number of storage locations, each can be identified with a unique address
What is ROM and what information is stored in it
Read-Only Memory is non-volatile storage that cannot be changed. It stores BIOS for when the computer is switched on which will then load the operating system.
What is Virtual Memory
Computers use the HDD instead of RAM if RAM becomes too full. New data will be stored in RAM and unused data will be stored in Virtual Memory
Describe secondary storage and the characteristics
Non-volatile storage which can be accessed repeatedly. Capacity, cost, durability, portability, reliability and access speed
Describe secondary storage and the characteristics
Non-volatile storage which can be accessed repeatedly. Capacity, cost, durability, portability, reliability and access speed
Name the types of Magnetic storage and the characteristics
Magnetic HDD, floppy disk and magnetic tape which involves a disk platter and magnetic field to read/write data. Large capacity and cheaper than solid state, not durable or portable. Slow access but faster than optical
Name the types of Optical storage and the characteristics
CD, DVD and Blu-ray which involves a laser projecting beams of light onto a spinning disk. Portable, cheapest, low capacity, not durable and slow access speed
Name the types of Solid State storage and the characteristics
No moving parts SSD, USB and SD. High capacity but expensive. Durable and small and portable, fast access too
Why do computers use binary
Computer systems consist of millions of tiny transistors which are switches with only two values: 1,0. Therefore all data must be represented and processed this way.
List the units of data from smallest to largest
Bit = 1
Nibble = 2
Byte = 4
Kilobyte = 1000 bytes
Megabyte = 1000KB
Gigabyte = 1000MB
Terabyte = 1000GB
Petabyte = 1000TB
Why is Hexadecimal numbers are used as an alternative to binary
It’s used as a shorthand for binary because it uses fewer character to write the same value. This makes hexadecimal less prone to errors when reading and writing it, compared to binary
Explain what an overflow error is
When a binary value is too large to be stored in the bits available
What effect does shifting to the left/right have on the binary value
Left: multiply
Right: divide
What is a character set and why are they needed
A table that matches together a character and a binary value. Each character in a character set has a unique binary number that matches with it. They are necessary as they allow computers to exchange data and humans can input characters
Describe three differences between ASCII and Unicode
ASCII: does not take up space, uses 1 byte and is enough for the english language
Unicode: allows 2 bytes, different languages however takes more space.
What does ‘ASCII’ stand for
American Standard Code for Information Interchange
Describe 3 differences between bitmap and vectors
Bitmap: made of pixels, each have an assigned binary value, depends of resolution
Vectors: drawn by precise mathematical instructions, smaller in file size, don’t lose quality
How do you calculate file size
File size = resolution x colour depth
Define resolution
The amount of pixels in an image
Define colour depth
The number of bits used to represent each pixel’s colour
How many colours represented in;
1 bit, 5 bits and a byte
1 bit: 2 colours
5 bits: 32 colours
1 byte: 256 colours
What is metadata and give 3 examples for a graphics file
The additional data about a file, this ensures the dimensions of image can be displayed correctly. Colour depth, File type, Resolution
How is an analogue sound wave converted into a binary sample
They must be digitally recorded and stored in binary. The amplitude is measured and recorded in binary as specific intervals
Define sample rate
The number of times per second the amplitude of a sound wave is measured
How is an audio file affected when sample rate is increased
The higher the sample rate, the better the audio quality is
What are the benefits of compressing a file
Takes up less storage, can be transferred quicker, can be read from or written quicker
What are the differences between lossy and lossless compression
Lossy: Removes data which can’t be seen or heard by humans, removes data permanently and is often used with videos and audios
Lossless: Doesn’t permanently remove, usually larger and is done for executable files and word documents
