The hard disk is the main storage device in your computer. It is a bit like a filing cabinet: all of your data files and applications software are stored on it. The hard disk contains a number of metal platters which have been coated with a special magnetic material. The data is stored in this magnetic material. Thus, the hard disk is known as a magnetic storage device. In order to access the data, the platters spin many thousands of times a second and a magnetic read and write head floats just above the surface of the platter. When you hear the term 'hard disk crash', this refers to the read/write head crashing down onto the surface of the hard disk. There is a risk every time this happens that the data stored in the section just where the head crashes might be damaged. That is why it is a bad idea just to switch the computer off at the wall without shutting it down properly. Hard disks are measured in Gigabytes. A typical hard disk size will be around 120 Gb - 1 Terabyte. It is possible to also have an external hard disk which can be plugged into the computer and used to back up your data and then stored in a different place to keep it safe.
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necessary to support the way your computer works
large storage capacity
stores and retrieves data much faster than a floppy disk or CD/DVD •
Stored items are not lost when you switch off the computer •
Cheap on a cost per megabyte compared to other storage devices Disadvantages
Far slower to access data than ROM or RAM chips
Hard disks can crash which stop the computer from working •
Regular crashes can damage the surface of the disk, leading to loss of data in that sector •
The disk is fixed inside the computer and cannot easily be transferred to another computer.
This section is dedicated to the GCSE ICT course. You will find revision notes, exam questions, mini websites explaining every topic you need to cover. Teachers will find starters and plenaries along with Schemes of Work ( SoW) , lesson ideas and tons of free material. Revision resources for GCSE exams cover systems, databases, data communications, legal issues, measurement and control, hardware, software, and modelling.
Floppy disks are one of the oldest types of portable storage devices still in use, having been around since the 1980s. However, they are gradually becoming obsolete and some manufacturers are now starting to build their PCs without floppy disk drives. A floppy disk can store up to 1.44 Mb of data which is equivalent to around 300 pages of A4 text. They used to be the ideal storage device for transferring small files from home to work/school or from one office computer to another. But nowdays, many files contain graphics or WordArt and are larger than the size of the floppy disk. Floppy disks are a magnetic storage device.
All disks must be formatted before data can be written to the disk. Formatting divides the disk up into sections or sectors onto which data files are stored. In the past, the user would have to format their own disks, but now they are sold pre-formatted.
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Portable - small and lightweight
Useful for transferring small files between home and school •
Security tab to stop data from being written over
Can be used many times
Not very strong - easy to damage
Data can be erased if the disk comes into contact with a magnetic field •
Quite slow to access and retrieve data when compared to a hard disk •
Can transport viruses from one machine to another
Small storage capacity
Many new computers don't have floppy disk drives
7. Zip Disks
Zip disks are pretty much obselete now. However, they were very popular as a...
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