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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
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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
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