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