Bayangkan anda menggunakan PDA untuk membeli hadiah untuk isteri dan anak-anak ketika tersangkut di dalam kesesakan lalulintas. Anda juga boleh memeriksa e-mel ketika tiba di lapangan terbang sebuah negara asing. Capaian maklumat di mana sahaja dan pada bila-bila masa merupakan sebuah janji daripada rangkaian data tanpa wayar. Namun realiti tidak seperti yang dinyatakan.
Dalam dunia yang lebih nyata, anda akan mendapati bahawa anda akan berada di luar capaian rangkaian selular dan sistem e-mel tidak dapat dicapai kerana ia tidak disokong oleh negara asing tersebut. Secara realitinya terdapat banyak kelemahan dalam capaian tanpa wayar dan pengguna harus faham bahawa ia berbeza daripada satu rangkaian kepada satu rangkaian yang lain dan daripada satu peranti kepada satu peranti yang lain. Pengguna juga harus faham mengenai tugas penyedia perkhidmatan tanpa wayar dan hubungan mereka dengan pembawa talian tanpa wayar.
cuba pautan ini :
http://history.sandiego.edu/GEN/recording/computer1.html#gp05
Tuesday, May 27, 2008
COMPUTER
A programmable machine. The two principal characteristics of a computer are:
· It responds to a specific set of instructions in a well-defined manner.
It can execute a prerecorded list of instructions (a program).
Modern computers are electronic and digital. The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called software.
All general-purpose computers require the following hardware components:
· memory : Enables a computer to store, at least temporarily, data and programs.
· mass storage device : Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.
· input device : Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.
· output device : A display screen, printer, or other device that lets you see what the computer has accomplished.
· central processing unit (CPU): The heart of the computer, this is the component that actually executes instructions.
· It responds to a specific set of instructions in a well-defined manner.
It can execute a prerecorded list of instructions (a program).
Modern computers are electronic and digital. The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called software.
All general-purpose computers require the following hardware components:
· memory : Enables a computer to store, at least temporarily, data and programs.
· mass storage device : Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.
· input device : Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.
· output device : A display screen, printer, or other device that lets you see what the computer has accomplished.
· central processing unit (CPU): The heart of the computer, this is the component that actually executes instructions.
Subscribe to:
Posts (Atom)
