Storage devices

Importance of memory size

Having more memory means applications run faster in their own, more applications can run at the same time and you can move quickly between applications.

CD-ROMs

Hold around 650 mega bytes. They are used mainly for the distribution of software. You can read a CD using DVD drive but you cannot read a DVD with CD drive, that's why software is still being sold on CD rather than DVD. CD ROM is data read only, data is stored as an optical pattern.

CD-Rs

The R stands for recordable. These are sold as blank CDs and can have data written on to them but only once. After that the work in the same way as CD-ROMs. It is ideal for the backing up of the data or for storing digital music.

Backing store

A backing store is also known as secondary store is any data storage area that the CPU uses of its ROM and RAM

Bit

A binary digit 0 or 1. Computers consist of electric circuits and each must be either turned on or off. This is why computers use binary code to represent data. If the circuit is turned on it is 1 and if it is turned off it is 0.

Solid state drives

A solid state is use to store data and it used in a similar way to hard drive except unlike a hard drive there are no moving parts. This makes them ideal mobile devices

Conversions of all bytes

Byte - 8 bits Kilobyte - 1000 bytes Megabyte - 1000 kilobytes Gigabyte - 1000 megabytes Terabyte - 1000 gigabyte

DVD-RAM

DVD RAM drive allow repeated storage and erasure of data so they act a bit like hard drive

DVD+RW

DVD RW can be used to write to as well as read data from a DVD. Typical storage capacities are 4.7 Gb for the older DVD drives

DVD and Blu-Ray

DVD are like CDs but hold much more data up to 8.54 gigabytes a side. Blu-Ray discs are like DVDs but again hold much more data nearly 6 times as much as a standard DVD. They are used for storing films in high definition

DVD-ROM

DVD have a much higher storage capacity than CDs and are ideal for the storage of multimedia files such as MP3, digital images and video clips. DVD ROM is used for distribution of movies where you can only read the data off the disk

Devices that have memory

Desktop,laptop, netbook and computer - large amounts of memory, which allows them to run multimedia software and run many all,I cations at the same time Mobile phones - to store programs to control the phone, address book details, games, digital music and photograph PDAs - to store programs such as the operating system, web browser software, address book details Palmtops - to store programs such as the operating system simple applications such as word processing, web browser software

ROM - Read Only Memory

Fast permanent memory used for holding instructions needed to start the computer up. ROM is help on computer chip. It is non volatile memory because it does not lose its contents when the power is turned off. Contents cannot be altered by the user

RAM - Random Access Memory

Fast temporary memory where programs and data are stored only when the power is supplied. RAM is held on a computer chip. It is volatile memory because the contents disappear when the power is turned off. It's memory can be read from and written to.

Flash memory

Flash memory is a type of non volatile memory which can e used to store gigabytes of data. Flash memory is a lot slower than the computers main RAM, but is often faster than a hard disk

Memory sticks

Flash memory's often sold in pen sized devices that you can easily connect to your computer using a USB socket. USB stands for Universal Serial Bus. They allow you to easily transfer data between computers. The main disadvantage is that they are easily lost or stolen.

Why do you need to know about the sizes

It is important to know about sizes because it is essential if you want to know how many of them could be stored on a particular device

Magnetic tape

Magnetic tape are used to back up large amounts of data for security purposes relatively cheaply. However access time is slow because read and write head can't go directly to particular piece of data. This is called sequential access.

Memory cards

Memory cards are used by digital camera and some mobile phones and MP3 players. Many computers come with slots for memory cards which means that you can use them for reading and writing files just like a memory sticks

Online storage

Online storage means storing data on file servers of an ISP an Internet Service Provider instead of your own computer's hard disk. You can use online storage to back up your files Share your files with other people Access files from any computer with Internet access

Optical disc

Optical disc include Compact Discs (CDs) and Digital Versatile Discs (DVDs). They store data as pits on the surface of a reflective disc. The data is read by moving a laser beam across the surface of the disc and reading the change in posing of the reflected beams

Printer buffer

Printer memory used to store print jobs that allows users to go onto another piece of work or log off before their work is printed

DVD R

R stands for recordable. It allows data to be stored on a DVD but only once. It is ideal for the backing up of data, for storing digital music or for storing film

CD-RWs

RW stands for Re-Writable. They are like a CD-R but can have old data deleted and new data written onto the disc. Transfer rate is less and time taken to locate file is greater

Byte

The amount of data and instructions the computer can store in its memory is measured in bytes. 1 byte contains 8 bits.

Hard disks

The main benefit of hard drives is that they have large storage capacities and very high transfer rate. Hard drives are usually housed inside a computer but you can get portable hard drive for additional storage