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OCR GCSE Computing

OCR GCSE Computing. Chapter 2: Secondary Storage. Chapter 2: Secondary storage. Computers are able to process input data and output the results of that processing, but it would be difficult if we had to keep re-entering all the data and programs every time we wanted to use the computer.

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OCR GCSE Computing

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  1. OCR GCSE Computing Chapter 2: Secondary Storage

  2. Chapter 2: Secondary storage • Computers are able to process input data and output the results of that processing, but it would be difficult if we had to keep re-entering all the data and programs every time we wanted to use the computer. • Secondary storage is used to store data and programs when the power is switched off: • RAM is volatile so the contents are lost if the power is switched off; • ROM can only store pre-programmed data and programs.

  3. Chapter 2: Secondary storage Magnetic hard disk: • Currently the most common type of secondary storage with very large capacities and good access speed. • The magnetic hard disk : • is reliable; • has a high capacity at low cost; • can be an internal device or external portable device for backup or transfer of large amounts of data; • stores the operating system, user data and programs.

  4. Chapter 2: Secondary storage Optical disk: • CD (compact disk) or DVD (digital versatile disk) • can be read only or read / write • CD/DVD ROM used to distribute programs • CD/DVD R/W used to store, transfer or backup data and programs • high capacity at low cost • small and easy to distribute • robust and can be used many times • CD 700MB, DVD 4.7GB typical capacity • slower than other media such as hard disk and flash ROM

  5. Chapter 2: Secondary storage Flash (solid state) memory: • Electronically alterable Read Only Memory • used in portable devices such as cameras, MP3 players, tablet computers and mobile phones • used with a USB interface as a backup / transfer medium for personal files • fast access times • reliable with no moving parts to go wrong • low power use • small, light, robust and highly portable • inexpensive at relatively low capacities but expensive at higher capacities.

  6. Chapter 2: Secondary storage When choosing which type of secondary storage to use, you need to consider: • Capacity – how much data does it need to hold? • Speed – how quickly can data be transferred? • Portability – does it need to be portable or used to move data from one system to another? • Durability – is it easily damaged? • Reliability – is it subject to deterioration over time or with repeated use?

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