|
|
|
| Software & Hardware | Central processing unit (CPU) | Storage Devices | Operating System (OS) | ||
| Application Software | Computer Communication | Chinese Input System | Useful Link | Your Comments | Quiz Zone |
|
|
¡@
¡@ ¡@
¡@ ¡@ ¡@ ¡@
¡@ ¡@ ¡@ ¡@ ¡@ ¡@ |
¡@
Computer store programs and data in two different ways: Main Memory and Backing store. Main memory temporarily stores programs and data that are being processed. It can be thought of as a series of storage locations. Programs and data are made up of characters. They are stored in the memory character by character. Each character is stored in one memory location in the form of bit pattern. When you type a character on the keyboard, the electronic circuitry interprets the character and stores it in the main memory as a code. In the past, data were stored in vacuum tubes and core memory. Today, semiconductor memory is used in almost all computers. It is so small but is very powerful. Memory sizes The size of the main memory is measured in kilobytes (KB), which is equal to 1024 bytes. For convenience, we sometimes round of the value of K to 1000. For example, 640 KB is approximately 640 000 bytes (640 * 1000). To measure of larger sizes, we use megabytes (MB) and gigabytes (GB).
The storage capacity of today's drive has increased a lot. In a few years ago, the storage capacity of a typical desktop system is about 100MB. For now, the microcomputers commonly found in the market are about 64MB to 500 MB, some may even up to 1.2GB, 12 times larger, and much faster. Of course, the range of the price is also vary. Backing storage devices Backing storage devices exist to save programs an data for future processing. All programs and data are not possible to be saved in the main memory as the main memory is very expensive. Also the program may be so large that it is impossible for the main memory to hold all the data. Backing storage devices can be treated as input/output devices. The function as input devices when stored data are transferred to the computer for processing. They function as output devices when processed results are written to them. There are several types of common backing storage devices : floppy disk, hard disk, magnetic tape, and optical disk.
Hard Disk
Magnetic tape : There are mainly three types of magnetic types:
¡@ Optical disk The technology used for optical disks is the same used for audio compact disks (CDs). Information is stored using a beam of laser to burn holes in a thin coating of metal. Photos, movies and text are also be able to process. Optical disks for computer data storage are also known as CD-ROMs (compact disk read only memory). Data are written permanently on the disk and can only be read like read on memory. Data on optical disks are not easily erased or changed.
|
You are the
¡@ ¡@
|
News
Headlines !
backing store
