Where is the information stored on my computer?
What is ROM and RAM?
Your computer can process an amazing amount of information and can store it, sometimes permanently and sometimes temporarily. ROM (Read Only Memory) holds data that is key to the operation of your computer. It cannot be easily altered and remains in storage, unaffected as your computer is turned on and off. RAM (Random Access Memory) is only active when your computer is turned on. You can work with this data in a particular session, but when the computer is turned off, or crashes, some of the data may be lost if you haven't saved it. You can generally expand the amount of RAM in your computer with additional memory cards.
How is data measured?
Information or data is measured in bytes - a byte being approximately one character on the computer keyboard. These terms might sound familiar in terms of measuring data:
1 Kilobyte (KB) = 1024 bytes
1 Megabyte (MB) = 1024 kilobytes
1 Gigabytes (GB) = 1024 megabytes
1 Terabyte = 1024 gigabytes
1 Petabyte = 1024 terabytes.
If you look at any of the files in the 'My Documents' folder of Windows XP, you can hover the mouse over any file name and see the type of file it is, the name and the author, when it was last modified and the size of the file, e.g. 24.5 KB.
Certain files, such as photo images, sound files or movies are generally larger (more bytes) and require more storage space, as well as more time and bandwidth to download from or send via the Internet. Consider the difference between the size of an average 16 page Word document (.doc) file (97 KB) and an MP3 music file (3.5 MB) - the MP3 file is 37 times bigger!
Where is information stored?
Your computer will store your information on an internal hard disk, usually identified as your 'C:' drive. Your system and application software are installed on this drive, which is why, if you have had a serious system crash, you might have to re-install your Operating System (OS), e.g. Windows, as well as any applications you had previously installed, although such a circumstance is not common. There have been vast improvements in information storage with huge increases in the capacity of home computer's hard drives (currently from about 80 to about 400 GB), and of RAM (currently 256 MB - 1 GB).
What other devices can store data?
Information can also be stored on a variety of external devices such as floppy disks, USB flash drives (also known as memory sticks, pen drives etc), CD-ROMs and DVD-ROMs. As new devices have become available so the storage capacity has increased significantly. A 3.5'' floppy disk can hold 720 KB to 1.44 MB of data, while a CD can hold 700 MB and a DVD can hold 4.7 GB per side. A large-capacity USB port memory stick, which can be small enough to actually go on your keychain, can hold up to 3 GB or the equivalent of over 3000 floppy disks. Other small peripheral devices with huge storage capacity include the Apple iPod (primarily used for MP3-format songs), which can store 80 GB of data
The risks
The size of these devices, even those with staggering capacity, can make them extremely difficult to detect and monitor. They can be moved from computer to computer and can carry malware in addition to the official information the owner is aware of. They are easy to conceal and can be casually worn on a chain around the neck or tucked in a pocket. They are also unobtrusive when plugged into a computer. To control the risk of infection, administrators can introduce policies and user agreements to restrict the use of such devices and ensure that regular anti-virus and anti-spyware sweeps are done to reduce the risk of compromise.
It is also possible to install additional software programs, which although unobtrusive, provide an extra layer of protection to the computer, by ensuring that unwanted storage devices, or changes to the system, are prevented by enforcing a policy. Normally there is a one off or annual subscription fee for this type of software program.
To find out about malware and how to minimise the risks, take a look at the Net basics webpage in this section of the website.
Click here to return to the Very Basics.
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