Central Processing Unit
This is a second part of computer hardware that comprises of the following:
- Arithmetic/logic unit (ALU) which is the processing unit.
- Control unit (CU)
- Random Access Memory (RAM) which is sometimes called main memory and read only memory
STORAGE AND MEMORY
They are any physical device in or on which computer information can be kept. A microcomputer has two main types of storage. Its random access memory (RAM) represents temporary storage that the microprocessor uses for programs, work in progress, and various types of internal work-control information. The computer’s disk drives and other external storage media represent facilities for holding information on a more permanent basis, available but out of the way until it is needed by the microprocessor. A computer has other types of storage as well. Its read-only memory (ROM) is a permanent, non-erasable medium for holding necessary information, including startup instructions and input/output procedures. In addition, a computer uses various buffers—reserved areas of memory—as temporary holding areas designated for specific information, such as characters to be sent to the printer or characters being read from the keyboard.
Storage hardware provides permanent storage of information and programs for retrieval by the computer. The two main types of storage devices are disk drives and memory. There are several types of disk drives: hard, floppy, magneto-optical, and compact.
- Floppy Disks:
Floppy disk drives also store information in magnetic particles embedded in removable disks that may be floppy or rigid. Floppy disks store less information than a hard disk drive and retrieve the information at a much slower rate. Magneto-optical disc drives store information on removable discs that are sensitive to both laser light and magnetic fields. They can typically store as much information as hard disks, but they have slightly slower retrieval speeds.
- Hard Disks:
They are one or more inflexible platters coated with material that allows the magnetic recording of computer data. Hard disks provide faster access to data than floppy disks and are capable of storing much more information. Because platters are rigid, they can be stacked so that one hard-disk drive can access more than one platter. Most hard disks have from two to eight platters.
Hard disk drives store information in magnetic particles embedded in a disk. Usually a permanent part of the computer, hard disk drives can store large amounts of information and retrieve that information very quickly.
- Compact Disk Drive:
Compact disc drives store information on pits burned into the surface of a disc of reflective material. CD-ROMs can store about as much information as a hard drive but have a slower rate of information retrieval.
- Digital Video Disk:
A digital video disc (DVD) looks and works like a CD-ROM but can store more than 15 times as much information.
- Smart Cards:
A smart card, which is similar in size to a credit card or ATM card, stores data on a thin microprocessor embedded in the card. Two types of smart cards exist: intelligent and memory. An intelligent smart card contains a CPU and has input, process, output, and storage capabilities. In contrast, a memory card has only storage capabilities. When the smart card is inserted into a specialized card reader, the information on the smart card is read and, if necessary, updated.