1.2 Memory & Storage Flashcards
Key Words: Main Memory
This is the main storage within a computer, which the CPU has direct access to. This is RAM (Random Access Memory).
Key Words: RAM
Random Access Memory - stores all the open programs and files. When a program/file is loaded, it is opened from Secondary Storage, and stored in the RAM. This is so the CPU can access the program/file and its data quickly.
Key Words: ROM
Read Only Memory - stores the program (BIOS) for booting up the computer
system.
Key Words: BIOS
Basic Input/Output System - the program that stores all the instructions for booting up the computer system, such as instructions for the input devices to work. It also loads the Operating System, which allows the user to actually interact with the device.
Key Words: Volatile
This means when the device is turned off (there is a loss of power), the contents of the memory are all deleted/lost. RAM is volatile, ROM is not volatile.
Key Words: Rewritable
This means the contents of the memory can be changed. RAM is rewritable, ROM is read only (not rewritable)
Key Words: Virtual Memory
Virtual Memory refers to how the computer continues to operate once the RAM becomes full.
Rather than stop working when the RAM becomes full, the computer partitions (splits off) a section of the internal hard drive (secondary storage). This section then acts as additional RAM, allowing the computer to continue functioning.
However, this greatly affects the performance of the computer, slowing it down. This is because data must be swapped between the virtual memory and RAM when being actively used.
Key Words: SSD
Solid State Drive - This is an example of Flash Memory. It acts as a permanent storage in a computer system. It behaves in the exact same way to a Hard Disk, however, is much
lighter and can work much quicker, due to having no moving parts. However, it is more expensive than a Hard Disk, and therefore is still emerging.
Key Words: Secondary Storage
This is where we store for longer than just whilst the computer is turned on. It is not volatile, and therefore data remains even after the power has been turned off.
Key Words: Optical Storage
This is a type of Secondary Storage.
Optical Storage is used within an Optical Drive,
where a laser is shone at the surface of the disc, and then processing the reflection from the disc. Optical Storages are discs, and examples are CDs, DVDs, and Blu-Rays.
CD-R, DVD-R – Read Only, so the contents cannot be changed.
CD-RW, DVD-RW – Rewritable, so the contents can be changed.
Key Words: Magnetic Storage
This is a type of Secondary Storage.
Data is stored on Magnetic Storage via magnetised dots. Magnetic Storage often has moving parts. An example of Magnetic Storage is an Internal Hard Disc Drive.
Key Words: Solid State Storage
This is a type of Secondary Storage.
Data is stored on Solid State Storage via electricity. It is becoming increasingly popular as its capacity increases, and its cost decreases. Examples of Solid State Storages are Memory Sticks, SSDs, and SD Cards.
Key Words: Capacity
Refers to the amount of data that can be stored on the media. The higher the capacity, the more data it can store without becoming full.
Key Words: Speed
Refers to the speed in which the data can be read and transferred. The higher the speed, the faster data can be read and transferred to and from the media.
Key Words: Portability
Refers to how easy the media is to transport and move around from one place to another. The better the portability, the easier it is to move the device from one place to another.
Key Words: Durability
Refers to how robust the media is, how likely it is to break when shaken or dropped. The better the durability, the less likely the device is to break or lose data if dropped or shaken.
Key Words: Reliability
Refers to how likely it is to be able to be used repeatedly, without failing. The better the reliability, the less likely the media is to fail over time.
Key Words: Units
Used as a measurement of storage.
The order is:
Bit
Nibble (4 bits)
Byte (8 bits)
Kilobyte KB (1000 bytes)
Megabyte MB (1000 kilobytes)
Gigabyte GB (1000 megabytes)
Terabyte TB (1000 gigabytes)
Petabyte PB (1000 terabytes)
Key Words: Binary
This is the language of the computer. Binary is used to represent all data within a computer system. It refers to transistors opening and closing allowing electricity to pass through or not, which is then represented using 1’s (ON) and 0’s (OFF).
Key Words: Denary
Our number system which uses 10 digits (0-9)
Key Words: Overflow Error
Occurs when two binary numbers are added together, and the resulting number has 9 bits rather than 8. The 9th bit cannot be stored and is therefore lost.
Key Words: Binary Shift
The process of moving bits within a binary number either to the left (binary shift left) or to the right (binary right shift).
A right shift effectively halves the original number, and a left shift effectively doubles the original number.
Key Words: Hexadecimal
Also called a base 16 system as it uses 16
characters (0-9, A-F).
A = 10
B = 11
C = 12
D = 13
E = 14
F = 15
Key Words: Character Set
The characters that are defined and recognised by the computer hardware and software. The size of the character set is dependent on the number of bits being used per character.
Key Words: ASCII
Has a character set of 128 characters, as it only uses 7 bits per character.
Extended ASCII has a character set of 256 characters, as it uses 8 bits per character.
Key Words: Unicode
Unicode uses 16 bits, giving a range of over 65,000 characters.
Key Words: Pixel
An individual ‘square’ on an image. Images are made up of millions of pixels. The more pixels the greater the quality of the image. Each pixel is a colour which is represented in binary.
Key Words: Metadata
Additional data stored about the image which allows the computer system to build the image on the screen. Some data stored here is the height of the image (in pixels), the length of the image (in pixels), the bits per pixel, GPS location etc.
Key Words: Colour Depth
Refers to the number of bits per pixel, and therefore the number of colours that can be
represented in an image. The greater the colour depth the more colours that can be in an image, however the larger the file size will be.
Key Words: Resolution
Refers to the number of pixels within an image.
The greater the resolution the better the quality of an image will be, however the larger the file size will be.
Key Words: Sound Sampling
Refers to the process of converting an analogue wave into a digital wave. The computer takes measurements of the wave at different time intervals known as a sampling interval. Each sampling interval is stored as a binary number. These samples are then pieced together to create a digital wave.
Key Word: Sample Size
Total number of bits in a sound. Can be calculated by multiplying the bit depth by the number of samples per second, multiplied by the number of seconds.
Key Words: Bit Rate
Refers to the number of bits (or amount of data) stored per sample. The higher the bit rate, the better the quality of the sound. The bit rate for audio is often referred to as kbps (kilobytes per second).
Key Words: Sampling Frequency
Refers to the number of samples stored per second. The greater the number of samples the better the digital wave will represent the original analogue wave.
Key Words: Compression
The process of reducing the size of a file by changing its attributes. There are two types of compression, lossy and lossless.
Key Words: Lossy Compression
A type of compression. This reduces the size of the file by permanently removing data. Lossy compression can be used on files such as images with little to no difference from the original (depending on the level of compression).
Key Words: Lossless Compression
A type of compression. This reduces the size of the file by rewriting the data in a more efficient way. No data is lost or deleted when lossless compression is used. Lossless compression can be used on files such as spreadsheets or text documents where data cannot be erased/removed.
