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