Storage The two types of storage: Primary Storage Secondary Storage.
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Transcript of Storage The two types of storage: Primary Storage Secondary Storage.
StorageThe two types of storage:
Primary StorageSecondary Storage
Primary storage is also called Main Memory
Primary Storage
RAM ROM
Random Access Memory
Volatile- data lost if computer switched off
Short term storage of data
Read Only Memory Non-volatile- data
remains when computer is switched off
Long term / permanent storage of data
Difference between RAM and ROMRAM- is only filled after a computer has been turned on and given something to do.
ROM- holds data and instructions necessary for starting up the computer when it is switched on.
Next session….Secondary StorageNext Session
Secondary Storage
Is needed to store data and programs needed for later use.
Types of Secondary storage devices:
Magnetic Disks
Floppy disk Advantages:1)cheap to buy2)useful in
transferring 5.25” data
Disadvantages:1)very unreliable at
times 3.5’’
Magnetic Disks
Hard Disk Advantages:1)very fast to
access data since data can
be accessed directly
Magnetic TapeAdvantage:
Disadvantages:1)it is small
1)accessing data 2)It is cheap is very
slow3)It can store lots of data
Optical Disk
Compact Discs (CD) and Digital Video Discs (DVD)
Advantages:1)Can store lots of data (more than
floppy)
Flash Memory
Flash memory is a type of constantly powered nonvolatile memory that can be erased and reprogrammed in units of memory called blocks
Types:USB Flash drive / pen driveUSB stands for Universal Serial Bus
Memory CardA memory card or flash card is an
electronic flash memory data storage device used for storing digital
information
What is SD?Secure Digital (SD) is a nonvolatile
memory card used extensively in portable devices, such as mobile phones, digital cameras, GPS navigation devices, handheld consoles, and tablet computers.
Secondary storage is also known as
Backing Store or Auxiliary Storage
Things to know:It is always slower to access data from backing storage than from main memory.
Data stored in backing storage is permanent so it is NOT lost when the computer is turned off.
Data stored in main memory is lost when the computer is turned off.
Next classWhat are the other types of Rom Write notes on the types of ROM
Class ActivityLook at the table in your text that
lists the storage devices (pages 38 & 39), their storage capacity and advantages and disadvantages.
Copy parts of the table into your notebook
QuestionsWhat is the difference between
CD-R and CD-RW?What is the storage capacity for
hard disks measured in?What is the storage capacity for
modern flash drives measured in?List the types of magnetic disks.
Components of a hard diskDraw and well labeled diagram for
a hard disk showing: sectors, tracks, cylinders, read-write heads, etc
VideoHow a hard drive works
Complete the following chart
Storage
Primary
RAM ?
?
Magnetic tape ?
Hard Disk ?
Optical Disk
? ?
?
Memory Card ?
Past Paper QuestionsAttempt ALLMay 2013 Q3Jan 2009 Q2Jan 2014 Q3Jan 2013 Q3
Access Methods
This term is used to refer to the mechanics of locating specific data at a particular place on a storage medium.
There are 2 types of access methods:
Direct AccessSequential Access
Direct AccessThis means that you can go
directly to a specific piece of data without having to access any other data either before or after the data you want
Sequential AccessMeans that data is retrieved
(accessed) in the order in which it was stored