The Organization of a Computer
Any computer can perform
the four basic operations of Input, Processing, Output, and Storage (IPOS).
These operations constitute the IPOS cycle. The internal design or structure of
a computer may differ from one system to another though the basic operations
remain the same. Figure 1.1 provides a block diagram of a computer. The figure
displays all the functional units of a computer which carry out the basic
computer operations. The lines in the figure indicate the flow of instructions
and data, while the Control Unit and the Arithmetic/Logical Unit together
direct the flow of control in the central processing unit.
Input Unit
Data and instructions are
entered into the computer through the input unit to get processed into
information. Input devices like the keyboard, the mouse, or the microphone are
used to enter the data. The data is entered in various forms depending on the
type of input devices. For instance, a keyboard can be used to input
characters, numbers, and certain symbols; a mouse is a device that has an
on-screen pointer that enables the users to select items and choose options; a
microphone can be used if the user wishes to enter instructions by making a
voice entry.
Regardless of the ways in which the input devices receive the inputs, the input
interfaces convert them into binary codes, i.e., 0s and 1s, as the primary
memory of the computer is designed to accept data only in this format. Several
advancements can be seen in input devices with devices like cordless keyboards,
optical mouse, laser mouse, cordless mouse, etc., being introduced in the
market.
Central Processing Unit
The actual processing of
the data is carried out in the Central Processing Unit (CPU), which is the
brain of computer. The CPU stores the data and instructions in the primary
memory of the computer, called the Random Access Memory (RAM) and processes
them from this location. The Arithmetic Logic Unit (ALU) and the Control Unit
(CU) are the two subcomponents of the CPU. The ALU carries out the arithmetic
and logical operations while the CU retrieves the information from the storage
unit and interprets this information. The CPU also consists of circuitry
devices called cache and registers.
Arithmetic logic unit
The data and instructions
stored in the RAM are transferred to the ALU for processing. The ALU performs
the logical and the arithmetic operations on the data and the results are
temporarily stored in the RAM. After the processing, the final results are
stored in the secondary memory, i.e., the storage unit, and are released
through an output device.
Control unit
The CU obtains the program
instructions stored in the primary memory of the computer, interprets them, and
issues signals that result in their execution. It helps in maintaining order
and directs the operations of the entire system. It selects, interprets, and
ensures the proper execution of the program instructions.
Processors
Some computers use more
than one processor for processing in order to reduce the load on a single
processor.
Output Unit
The output unit passes on
the final results of computation to the users through the output devices like
the monitor, printer, etc. A monitor displays the final results of the
processed data on the screen while a printer can be used for obtaining the
output in a printed format. These output devices link the computer with the
users. The output interfaces convert the binary code produced by the computer
into the human-readable form.
Storage Unit
Before the actual
processing takes place, the data and instructions that enter the computer
system have to be stored internally. Also, the final results generated by the
computer after processing has to be stored before being sent to the output
unit. The storage unit of a computer system is designed to store the data
generated at various stages of processing. Storage media like hard disks,
floppy disks, etc., aid in storing the data in various forms. The hard disk is
an integral part of the computer system. It is also referred to as hard drive,
disk drive, or hard disk drive. The hard disk provides a large amount of
storage space for the programs and data. Computers these days feature a hard
disk that has several gigabytes of storage capacity. The floppy disk drives,
CD-ROM/CD-RW drives, DVD drives, and USB ports enable the user to store and
exchange data with others using storage media like floppy disks, compact discs
(CDs), digital video discs (DVDs), and pen drives.
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PREPARED BY :
< MOHD SYUKRI BIN MAT LAZIM >
< B031310013 >