you have a letter open and are looking at or working on it the computer stores it in memory. All the software currently running is stored in memory too. This kind of memory is called RAM (Random-Access Memory). Random-access means that any part of the information may be read or changed randomly, the computer does not have to look through all the data in order so that it can find the right piece. There is another kind of memory called ROM (Read-Only Memory). Read-only means that the data on it cannot be changed. ROM is used to store basic information that every computer needs.
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Random-access memory RAM is used to store the data the computer is currently using.
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Read-only memory ROM is used to store the basic information that every computer needs.
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When a computer is turned off, everything in RAM is erased. Because this would cause you to lose your work all the time, disks were created. Disks are round flat objects, but in computer slang they are pieces of data storage hardware that do not need electricity to keep the data stored. There are other things that do this that are not disks, however the things inside of all things called disks are round and flat, so that is how the term came to be. All disks need to be in another piece of hardware that acts as an interface between them and the rest of the computer called a drive.
There are two main kinds of disks: Magnetic and Optical. Magnetic disks are the old kind and are slowly being replaced. They store data by aligning little pieces of metal inside differently using a magnet. Because of the way they store data magnetic disks can be erased or completely destroyed by magnets, heat, and dust. The two most popular forms of magnetic disks are Hard Disks and Floppy Disks. Hard disks are stored permanently inside their drive, which is normally installed into the computer box where you cannot see any part of it. Hard Disks can store a lot of data, and are used to store most of the information on computers. Floppy disks are small disks that you can pop in and out of their drive. All you can see of their drive is a slit in the computer box with a button and a light. You can put in different disks and then take them out and give them to someone so that you can transfer data between your computers.
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Hard disks Hard disks are used to store most of the data on a computer, and can store more than anything else can.
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Floppy disks Floppy disks are used to transfer data between computers, but are very small.
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Optical disks are the newer kind of disk. The most popular kind of optical disk is the Compact Disc (CD). CDs can still be put into and taken out of their drive, making them good for buying programs on, and nowadays for transferring data. Normal CDs that you buy with programs on them are CD-ROMs. They are called that because, like ROM, they are read-only. You can also get CD-Rs and CD-RWs, which are not read-only and are not erasable and erasable, respectively. Unlike floppy disks that can store only 1.44 megabytes (MB, that’s 1 048 576 bytes, usually we estimate that it is one million), CDs can store around 700MB! And, because CDs store their information with variations in the shape of the disk that reflects a laser differently they cannot be damaged as easily. However, you should still never touch the shiny surface of the CD. Digital Versatile Discs (DVDs) are another kind of Optical disc that work identically to CDs, however they can store much more information and transfer it at much higher speeds. There is also a new format coming in from Japan that is smaller and faster than DVDs and stores much more information! Today you can also get memory cards that are called flash memory or, more properly, EEPROMs. These are cards that operate just like ROM that isn’t read-only, so they don’t lose their information when the power is cut.
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Compact Discs CDs are the most popular form of optical discs.
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Digital Versatile Discs Sometimes called Digital Video Discs because of their extensive use in video, DVDs can store more than CDs.
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All data on a computer is stored in collections called files and folders. A file is the most basic collection of data on a computer. A file can store the instructions for a single program, or the data for a single letter. Folders are collections of files. So a file is like a piece of paper and you put it in a folder.
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Files Files are the most basic data collections, they store the data for a single thing.
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Folders Also called directories, folders are collections of files.
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It is very necessary to sort files properly into folders so that you can find them again. Many people have had to redo entire projects because they lost their file by putting it into the wrong folder. Most files are named with two parts. The first part of the filename is a description of the file. After this comes a ‘.’ followed by the second part. The second part of a filename is called the extension. Extensions are often three letters long and they tell you what kind of file it is. For example ‘exe’ files (files with an extension of ‘exe’) are programs. ‘Doc’ files are Microsoft Word documents.
Besides saving (taking a file you have open in a program and writing it from memory onto a disk) there are many other file operations. These can all be done using the same program. This program is a utility called a file manager. There is a file manager that comes with Windows called Windows Explorer, or sometimes just Explorer. To open Explorer go to ‘Start->Programs->Windows Explorer’ or Right Click Start, Click Explore, and the Directory should show. Yet in Windows XP, You go ‘Start->All Programs->Accessories->Windows Explorer’.
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NOTE: This is a standard computer notation for menus. When you see something that goes ‘M1->M2->...’ or sometimes ‘M1 > M2 > ...’ it means that you are to open the menu item M1 and then open the sub-menu M2 etc. and the final item is the menu item to click on. Obviously, ‘Start’ is the start-
