Download Computer memory - i

Computer memory
Bits and bytes






Data can be stored and measured in bytes
One bytes can contains 8 bytes
A bits can only be 0 or 1
A series of 0 and 1 is known as a binary code
Every key character has a binary code
Computers only understand binary code
e.g. the word BAG will occupy 3 byte memory
 each storage location contains data such as a number, a character or a
string of characters, computer instruction, part of a picture or another
address of data
 One thousand and twenty four bytes make up a kilo bits
Types of memory
 ROM (Read Only Memory)
 Its permant, which means it doesn’t change or erase
 Its know as a “Non Volatile Memory”, because it doesn’t disappear after
switching your computer off
 ROM are not device or physical things





RAM (Random Access Memory)
Its different because its temporary
Only works when the computer is switched on
Its know as a “Volatile Memory”
Nothing is stored permant on RAM
 They both store data inside the computer
Data storage
Internal Backing Store
Hard disk are the main Internal Backing Store
Hard disks have large storage capacity
Are found inside the computer
Floppy disk drive
 Are not common anymore
It can be easily stored
Its not recommended
 Is a magnetic device
Flash drive
 They are small and light
 They are portable, removable and re-writable
 They use a USB port on the computer to transmit or receive data
 They are more fashionable looking
 Easy to transmit viruses
 if you put it near a metal all your data will
be erases
 You can easily lose your Flash Drive
 Its more expensive than CDs and DVDs
 It’s a optical device
DVD
 DVD- Digital Versatile disk
 Very similar to CD’s
 The memory contains more space
 You can store on one side and on the other side
 Make sure you buy the right format
 Produces a better quality of sound and image
 Are now very cheap
 A DVD player can read CDs and DVDs, but a CD player cant read a DVD
 There are many DVD formats
 Also they can be easily damaged
 Is a optical devices
Types of DVD’s:
 DVD minus R
 DVD plus R
 DVD minus W
 DVD plus W
DVD-R and DVD + R
 DVD-R can be played on most home DVD player
 DVD-R media is at the moment the cheapest most
common
 Can only be used in DVD Recorders and Burners that
support DVD-R recording or multi-format recording
 Its rewriteable
 Has a 4.7gb DVD disc
 The DVD+R disc type does not compare well with DVD-R as
far as DVD playback compatibility
 They can only be used in DVD Recorders and Burners that
support DVD+R
Magnetic tape
It’s a magnetic device
It can store large amount if data
Used to backup data
Large organizations use it
It uses serial access to data
Needs a special type of equipment to read or record
data
Over 100 GB memory capacity
Its cheaper to store data on them
CD-ROM and CD- Write
 CD-ROM (Compact Disk Read Only Memory)
 You can store data once, you cant add
 You can burn music and movies on to it
 They are optical devices
 Memory capacity 700 MG
 Make sure you buy the right format
Types of CD’s:
 CD write or also known as CDW