[ICT] Storage Devices
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Transcript of [ICT] Storage Devices
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STORAGE
DEVICESAN 2015
+Storage Devices vs Storage Media
A storage device
is something that has the ability to read and write information
to and from a storage media
Eg. CD/DVD writer
Storage media
The components that store the information
Eg CD/DVDs, Hard disks, etc
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Computer memory is any physical device
capable of storing information temporarily or
permanently.
All computers have memory that is used to
hold the program instructions that the CPU
executes. The CPU can also write to and
store information in the memory.
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Memory
Primary
RAM ROM
Secondary
Hard Disk CD DVD
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Memory
PRIMARY SECONDARY
RAM ROM
To store data permanently
• Hard Disk
• CD
• DVD
Aka ‘backing storage’
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Primary Memory
RAM ROM
is a Volatile memory
is temporary memory
is memory that loses its
contents when the computer is
turned off
the more RAM a system has –
the faster it will run
is Non-volatile memory
is permanent memory
is memory that keeps its
contents even if the power is
lost
usually used to store the
essential program drivers to
start the computer
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+Backing storage
Any type of data storage device apart from RAM or ROM
Used to store data permanently even when the computer is
turned off
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+How Computer Memory Is Measured
Bit
All streams of input symbols to a digital system are evolved with 2
distinct symbols. These symbols are 0 (zero) and 1 (one), and are known
as Binary Digits or Bits.
Byte
A byte consists of eight bits
Kilobyte
A kilobyte (KB) consists of 1024 bytes
Megabyte
A megabyte (MB) consists of 1024 kilobytes
Gigabyte
A gigabyte (GB) consists of 1024 megabytes
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+Secondary Storage Devices
[also known as . . .
. . . external memory and auxiliary storage]
Secondary storage is a storage
medium that holds information
permanently until it is deleted or
overwritten even when the computer is
turned off
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+Memory Terms
Main or Internal memory
RAM & ROM
Backing storage
Any other memory other than RAM & ROM
Serial or Sequential Access
Data is stored in a sequential sequence so that information stored canonly be accessed by scanning through the data to that point. Eg. Tapes
Direct or Random Access
Any piece of information stored on a random access device can beaccessed without having to scan through its whole contents. Muchfaster than serial access. Eg. CD, DVD
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+Backing Up – Backup Models
Unstructured Backup
Selecting files
Full System Backup
Incremental Backup
Backups after Full System Backup
Off-site Backup
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+Backup Solutions
Manually copying
Software backup
Mirroring (RAID)
Two or more hard discs are linked such that information is written to
both of them at the same time, creating clones
Online or Remote backup
Files backed up via the internet to an online server usually by a third
party software installed on computer. Cloud computing !
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+
Thank You
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