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Memory and storage:confetti_ball: - Coggle Diagram
Memory and storage:confetti_ball:
Virtual Memory
Advantages
:
uses cheap secondary storage on hard drive
prevents error messages saying 'out of memory'
Disadvantages
:
accessing virtual memory is slow
to access data the existing data in RAM needs to be copied to the virtual memory, then data in virtual memory must be copied to the RAM :
= part of the hard drive used as an extensions of RAM
to access data, the existing data in the RAM needs to be copied to the virtual memory then data in the virtual memory must be copied to the RAM
ROM
Definition : Read Only Memory
Non-Volatile
used to store the boot sequence instructions (starts the computer)
data in ROM is accessed by CPU
data on it cannot easily be overwritten by user
Solid State Flash Memory
Primary storage
RAM
Size
: 8Gib - 16Gib
Purpose:
to store programs that are currently bring used
help to enable 'multi-tasking
Definition
: Random Access Memory
Volatile
- it loses data when there is no power
Storage type:
Solid State, Internal Primary Memory
how it works
:
loaded from the hard disk onto the RAM
so CPU can access the data and instructions at an acceptable rate
Types of RAM:
Dynamic RAM, Static RAM
Solid State Drives (SSD):
Basic features
:
uses non-volatile flash memory to store information
very fast read/write speeds as it doesn't need to wait for disk to spin to the correct location and an arm to move
no mechanical or moving parts meaning that disks are very durable
Advantages
:
highly durable, no moving parts
very fast read/write speeds
no noisy fan or drive arm
faster start up times
Disadvantages
:
more expensive than magnetic hard disks
similar storage capacity as magnetic disks
Uses:
higher end computers
laptops
smartphones
Steady State Storage
Flash Memory
uses logic gates to configure layer of electrons
can read and write to it
uses positive and negative voltage to let 0s and 1s be equal to charges
uses NAND Circuit Gate Technology
sends a large electric current to force electrons through a barrier and trapping then in position
low cost, portable, no moving part, durable
this makes them more ideal for a range of offline devices:
cameras
mobile phones
USB memory sticks
non-volatile flash memory to store info
very fast read/write speeds as it doesn't ned to wait for disk to spin to correct location and arm to move
no mechanical or moving parts meaning these disks are very durable
Secondary Offline Storage
Optical Storage
Laser Beams reflects = 1
beam doesn't reflect in a pit = 0
CD-ROM
storage of small media files and documents
could only be used once, would be burned
DVD-ROM & Blu-ray
storage of larger media files and documents
Blu Ray - 3rd generation - best
Advantages
:
can skip to next track instead of fast forwarding it
cheap
very easily portabe
takes up little space physically
the amount of data that can be stored depends on the amount of small pits can be fitted into disc
Basic features:
data is stored as pits and lands burnt pr pressed into a spiral track circulating outwards from the centre
laser beam passes over the pits and lands on the level of reflection is measured
from the signal, 0s and 1s can be derived
Disadvantage
:
less storage capacity compared to other types
easily damaged/scratches, required a CD reader
slow write speeds
Uses
:
song, videos and other multi-media storage
backup and archiving data
Capacity
:
CD-ROM - up to 720MB
DVD - up to 8.4gb (dual layered disk)
Blu-ray - up to 50GB (dual layered disk)
Registers
Memory address register
Memory data register
Accumulator
Cache Memory
Hard Disk Drive
Magnetic disks
Basic Features
:
disks contain concentric circles called tracks
each trach is divided into sector
disks heads mounted on mechanical arms read and write the data
a disk with solid platter is a 'hard disk'
soft plastic disks = floppy disks
Fragmentation
:
as your save each file it will save it at random tracks, at the next available sector,
doesn't save similar files at a same locations - problem
magnetic platters contain data hard disks may contain more than one platter
drive read/write head read data on the drive using electromagnetics
actuator moves the arm
Magnetic storage: hard disk
fixed magnetic hard disks are still used in PCs and laptops:
have large storage capacity, up to 6TB
they are very cheap
Advantages
:
cheap
large storage
relatively fast writing speed
Disadvantage
:
lots of mechanical parts, durability an issue
-sealed into due to disk head and platter precision and not very portable
Uses
:
personal computers
storage of large quantities of data
Capacity
:
500GB - 12TB or greater
Cloud
where you are using internet services to store your data
can be split into 2 main areas:
cloud storage - Google drive, gmail
cloud computing - office apps - words + powerpoint,
Advantages
:
can access data anywhere, anytime with only once device
has more variety
automatically updates/ synchronizes to all devices
Cloud storage
allows users to access files and data on the Internet remotely
data may be stored into multiple locations
professional company will manage the data storage
Features
:
synchronisation of devices with the same cloud storage
24/7 availability
redundancy: has older versions that didn't work as well
multiple file versions (could make as many files as you wanted)
scalability
Redundancy
:
having more than one copy of files stored on a different hard drive or at different locations
storage redundancy is where multiple copies of files are stored in different locations
Scalability
:
the ability of the storage system or cloud computing resources to increase in size
cloud storage normally changes for the amount of storage used
Data centres
:
data centres are buildings that are dedicated to storing physical servers
each server will contain an array of hard drives
professional engineers will manage the computers
the buildings will have temperature control and air conditioning
uptimes (how long for data to upload and working for) for data centres are often better than 99.99%
Privacy
:
if data is stored in the cloud, the security and privacy of the data is controlled by an external company
data can be stored locally is under the control of a a single person or organisation
both cloud storage and local storage ay be hacked, however cloud storage will be more secure
companies are organisation will need to consider the level they trust an external company to hold their data
Data transfer speed:
when file is used on cloud storage it must be downloaded - with fast connection and small office documents this may happen in few seconds
however larger files (used in video editing) may take hours to open or save files to cloud storage
local storage is very fast to transfer data:
a local SATA can read and write at around 500MB per second
typical UK internet connection operates at around 70mB/s
Scalability
:
the ability to easily increase the size of computing storage or processing power
e.g. images , videos
Disadvantages
:
if company becomes hacked / bankrupt --> will affect us greatly
if Wifi is unavailable /
internet connection access
password lost