Friday, January 8, 2010

Computer Output and Storage Devices Definitions

Computer Output and Storage Devices Definitions
These are devices that relay out the processed data for end users to interpret and includes Monitor, printers etc
There are two types of Output
          Hard Copy output - printed on a paper
          Soft Copy Output - Display on the computer monitor also know as (WYSIWYG) output, What You See Is What You Get
Secondary Storage Devices (Auxiliary Devices)
These store the information externally from the computer System Unit. Primary memory is not large enough to hold the data available it is seldom volatile - when power is switched off it also goes off therefore loosing all the data it had stored
Secondary Storage - is non volatile and hence required for long term use for storage back up.
There are three types of storage medium namely
          Magnetic type
          Magnetic Discs
          Optical media
Computer Operating Systems (OS)
Is a set of programmes that controls and supervises computer system hardware and provide interfaces to Application Programmes and uses of computer systems resources. Its purpose is to provide an interface between a user or an application system and the hardware Control programmes manages computers hardware and resources
Control Programmes Performs
          Resource Management - Manages memories and CPU
          Job Memory - Manage different jobs at the same time
          Data management input and output management
Computer Utility Programmes - These perform routine checkups and maintained of the computer e.g.
Disc scanning and defragmentation examples includes
          Disc cleanup
          Disc Defragmenter etc
Service programmes - These provides services to users or programming of computer system e.g language translator programmes
Magnetic Tapes
Typically half inch or quarter inch of plastic writing material coated with magnetic material usually iron oxide, reading of magnetic tapes is sequential.
Magnetic Disc made of metallic printer in which electronic data can be stored reading is sequential or direct.
Advantages of Magnetic Discs
          Direct access to store data
          Faster data transfer speed
          Convenient fro small computers
          Relatively cheaper
There are two types of magnetic Discs
          Floppy Discs (Diskettes) Floppy Disc is a small flexible disc and usually available in 3 1/2 inches and 5 1/4 inches. Each diskette regardless of size is divided in concentric circle, where data is stored is stored. It is also divided into pie shaped wedges called sectors which further specified storage. The number of sectors is determined by dividing formatting process which is control by Computer operating system (OS).
The Operating System labels each sectors of each diskettes with an address so that computer can go directly into specific areas rather than starting at the beginning.
A diskettes maybe single sided where data is recorded mainly one side or double sided which allows information to be recorded and stored on both sides
Advantages of Hard Disc over floppy Diskettes
          Hard Disc has higher rotational speed
          Hard Disc has more storage capacity
          Hard Disc has faster access to storage of data
          Hard Discs
Hard discs are of two types
          Fixed disc system
          Removable cartridge
Computer Optical Technology Media
Involves the use of lacers and are secreted new types of storage media most are read only memory(ROM), however some can be written but they are more expensive to acquire and requires special machines for writing. They have very high memory.
Care Tips for the Diskettes
• Prevent dust from accumulating from them
• Don’t touch exposed parts
• Keep far from magnetic field
• Store in dry place
• Don’t bend floppy diskettes
• Keep away from direct sunlight

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