Microsoft Office Tutorials and References
In Depth Information
COM 4
ESSENTIAL INTRODUCTION TO COMPUTERS
WHY IS A COMPUTER SO POWERFUL?
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Computer
Programs
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Computer Programs.
A computer derives its power from its capability to perform the information processing cycle with
amazing speed, reliability (low failure rate), and accuracy; its capacity to store huge amounts of
data and information; and its ability to communicate with other computers.
HOW DOES A COMPUTER KNOW WHAT TO DO?
For a computer to perform operations, it must be given a detailed set of instructions that tells it
exactly what to do. These instructions are called a computer program ,or software . Before
processing for a specific job begins, the computer program corresponding to that job is stored in the
computer. Once the program is stored, the computer can begin to operate by executing the
program's first instruction. The computer executes one program instruction after another until the job
is complete.
WHAT ARE THE COMPONENTS OF A COMPUTER?
To understand how computers process data into information, you need to examine the primary
components of the computer. The six primary components of a computer are input devices,
the processor (control unit and arithmetic/logic unit), memory, output devices, storage devices,
and communications devices. The processor, memory, and storage devices are housed in a
box-like case called the system unit . Figure 3 shows the flow of data, information, and
instructions between the first five components mentioned. The following sections describe these
primary components.
FIGURE 3 Most devices connected to the computer communicate with the processor to carry
out a task. When a user starts a program, for example, its instructions transfer from a storage
device to memory. Data needed by programs enters memory either from an input device or a
storage device. The control unit interprets and executes instructions in memory and the ALU
performs calculations on the data in memory. Resulting information is stored in memory, from
which it can be sent to an output device or a storage device for future access, as needed.
PROCESSOR
CONTROL
UNIT
ARITHMETIC
LOGIC UNIT (ALU)
instructions
data
information
INPUT
DEVICES
OUTPUT
DEVICES
data
information
MEMORY
instructions
data
information
STORAGE
DEVICES
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