1.2 Memory and Storage Flashcards
Primary Storage
Memory that the CPU can access very quickly
Need for primary storage
For data it needs to access quickly
Examples of things stored in primary storage
Operating System
BIOS
Boot up instructions
Types of primary storage
ROM
RAM
Purpose of ROM in a computer system
Non - volatile
Contains BIOS for the boot process
Purpose of RAM in a computer system
Volatile
Operating system is copied into RAM from secondary storage when computer boots up
CPU can access quickly - stores data, files, and programs that are being used
ROM full form
Read-only memory
RAM full form
Random access memory
Volatile memory
Temporary
Needs power to retain data
Non - volatile memory
Permanent
Retains. data when there is no power
BIOS
Basic Input Output System
Instructions a computer needs to properly boot up
Virtual Memory
When RAM gets full, the computer moves less recently used data into a section of secondary storage (virtual memory)
For the CPU to read data in virtual memory, it needs to be swapped back into RAM
When is virtual memory needed?
When too many applications are running at once
Disadvantage of Virtual Memory
Makes a computer slow to respond when switching between applications (swapping them in and out of RAM)
Secondary Storage
Where data is stored when not in use
Need for secondary storage
To store files and programs
Common types of secondary storage
Optical
Magnetic
SSD
HDD
Hard Disk Drives (HDDs)
Stack of magnetised metal disks that spin
Have a read-write head which can read + write data
Solid State Drives (SSDs)
No moving parts = silent
Use a type of flash memory
Higher read-write speed than HDDs
Advantages of HDDs
Cheap
High capacity
Longer read-write life than SSDs
Advantages of SSDs
Faster
Don’t need to be defragmented (slows them down!)
Shock - proof
Silent
Optical Storage
Uses light to store data
Examples of optical discs
CD
DVD
Blu-ray
Types of Optical Discs
Read only (e.g. CD-ROM)
Write once (e.g. CD-R)
Rewritable (e.g. CD-RW)
Why use of optical discs is declining
Streaming services have become popular e.g. Netflix
Modern devices e.g. phones don’t have optical drives
Disadvantages of Optical Storage
Low capacity
Slow read/write speed
Poor reliability
Scratches
Advantages of Optical Storage
Cheap
Portable
Not affected by water or shock
Advantages of Magnetic Tapes
Large capacity
Cheap
Fast rad/write speed
Where are magnetic tapes used?
In archives of large organisations