1.2- Memory and Storage Flashcards
Secondary
This type of storage cannot be read directly by the CPU. It’s non-volatile and much bigger than primary. Examples are Hard Disk, USB Flash Drive, SSD, CD
Primary
This type of storage is also known as main memory or primary memory. It is volatile and can be accessed directly by the CPU
Random access memory
Primary Storage we can write to, also known as main memory. All data in use and instructions currently running are stored here. It is volatile.
Read only memory
Cannot be changed. Non-volatile semiconductor primary memory, contains the start-up instructions for the computer known as the BIOS
Volatile
Forgets all contents when powered off, RAM is this type
Non-volatile
Remembers all contents when powered off, ROM is this type
Write
We can do this to RAM but not ROM, it means change the contents
BIOS
The startup instructions for a computer, stored in ROM. It stands for Basic Input Output System
Virtual memory
Space in secondary storage that acts like extra RAM, so we can run more processes simultaneously
Process
Any part of a program that is currently running, this will need to be in primary memory so the CPU can execute it
Swapping
Moving a process from RAM to virtual memory to make more room in RAM for a new process
Thrashing
Constantly swapping processes between RAM and virtual memory because there is not enough RAM. Causes slow performance.
Running
Currently executing. (A process must be loaded in RAM before it can be executed)
Speed
How fast a secondary storage device can read and write data. SSDs and flash memory are fast
Durability
Ability of a device to withstand knocks and drops and still work, solid state devices are good
Reliability
How long a secondary storage device will last without breaking down or losing data, solid state devices are good at this
Cost
The price of a secondary storage device, SSDs are high
Portability
How easy it is to move a secondary storage device or its media around, CDs and memory sticks have this
Hard disk drive
High capacity magnetic secondary storage device. It has spinning platters so it wears out, making it less reliable and portable than SSD.
CD
Optical storage, a laser reads and writes the 700MB capacity optical disks. Disks are cheap and portable.
DVD
Optical storage, a laser reads and writes the 4.7GB capacity optical disks which are cheap and portable, but a bit more expensive than CDs.
Blu-ray disc
An optical storage component with a capacity of 25GB, a blue laser reads them, they are more expensive than DVDs but still cheap to make.
Solid state drive
No moving parts means this high capacity, fast, durable, low power and reliable secondary storage device is good for laptops but it’s expensive
Memory stick
A solid state storage removable storage device which is very portable, comes in capacities from 1GB up to 512GB
Memory card
A solid state storage device with a flat shape that is used in cameras and phones, also known as a flash card or SD card
Secondary storage
Non-volatile storage that stores programs and data. The OS, system software and application software are all installed here, plus files and folders. Comes in many types: magnetic, solid state and optical
Optical
A type of secondary storage that uses laser light to burn data onto a medium such as CD, DVD or Blu-Ray disc
Magnetic
This secondary storage type stores data by magnetising the surface, it includes hard disk drives and tape drives
Solid state
Secondary storage type with no moving parts, it uses semiconductor technology, and works by trapping electrons inside a gate. Includes SSDs, flash memory, memory sticks and SD cards
Capacity
The amount of data that can be stored in a storage device or on storage media. If you create lots of data you need this characteristic to be high
Speed
How fast data can be read from or written to a storage device. This characteristic is important if your application creates or uses a lot of data quickly such as a video
Binary
Data format that can be represented by electrical voltages, which can then be processed by logic gates in the computer
Decimal
Also known as denary, the numbers we use in everyday life, which cannot be processed by the computer
Encoding
Converting data into a binary format so that that it can be stored and processed. ASCII and JPEG are both examples