Central Processing
Unit (CPU)
Every computer is made of
hardware and software. The mechanical parts of a computer are called hardware.
And the organized collection of data and instructions in the computer is called
software.
FUNCTIONAL UNITS OF COMPUTER
Different hardware units of a
computer help it perform specific functions. Let us take up the functions of
the computer system one by one.
➤ Input
The process of entering data,
instructions and programs into the computer system is called input. Some common
input devices are keyboard, mouse, microphone, joystick, light pen, etc. The
input is processed by the computer in a systematic manner.
➤ Storage
Since the computer processes the
data provided by us at a very high speed, it is necessary that we provide the
data to it at the same speed. For this purpose, the data is stored in the
system at a particular allotted space for faster access and processing.
➤ Arithmetic and Logical
Processing
The instructions (given along
with the data) are sent to the storage unit. The Arithmetic and Logic processor
accesses the data stored in the storage unit and performs the required
processing in the form of arithmetic calculations and logical operations the
result is again sent to the storage unit.
➤ Output
The result, after processing, is
stored in the storage unit before changing it to user-readable form. It is then
displayed on the output devices such as monitor or visual display unit (VDU),
and can also be obtained on paper using a printer.
➤ Control
All the above listed tasks
performed by different parts of the computer are well-coordinated and
controlled inside the computer system.
The function of arithmetic and
logical processing as well as controlling and coordinating is jointly performed
by the Central Processing Unit (CPU) or simply the processor of the computer.
CENTRAL PROCESSING UNIT (CPU)
CPU is a small hardware component
of a computer system fitted inside the CPU cabinet or the CPU box. In large
machines, CPUs require one or more printed circuit boards (PCBs). PCBs are thin
plates on which electronic chips and other electronic components are soldered.
In personal computer and small workstations, the CPU is housed in a single
postage-stamp sized silicon chip called microprocessor. This chip is also
called an integrated circuit. Modern CPUs are small and rectangular structures
with multiple metallic pins on their underside. They are directly inserted into
the socket provided on the motherboard with the help of the pins. Intel and AMD
(Advanced Micro Devices) are two popular CPU microprocessor manufacturing
companies.
Do You Know?
CPUs are of different types and
each type comes with varying degrees of speed, memory and pre-set instructions.
The larger the CPU, the faster it can process, store and execute commands.
• A single-core CPU is the
smallest unit available. It is usually found in smaller devices that only
perform a simple set of actions such as a remote control or toy.
• Dual-core CPUs contain two
command units and have enough power and memory for most personal computers.
• Multi-core CPUs contain
multiple command units. They are mainly used by large industrial electronic
devices, servers and network workstations.
Functional Units of CPU
In the previous section, you have
learnt about the functional units of computer. Let us now learn about the
functional units of CPU.
The CPU has three main functional
units:
·
Control
Unit (CU)
·
Arithmetic
Logic Unit (ALU)
·
Registers
Control Unit (CU)
·
The control unit of the CPU is the controller
and coordinator, in short, the supervisor of the whole computer.
·
The control unit controls the sequence of
instructions and executed. programs to be
·
It controls the flow of information between the
ALU and the Registers.
·
It coordinates the functions of all parts of the
computer.
Arithmetic Logic Unit (ALU)
·
The actual processing of the data as per
instructions is done by this unit of the CPU.
·
It performs all mathematical calculations like
addition, subtraction, multiplication and division.
·
It performs logical operations like comparisons
such as greater than (>), less than (<), equal to (=), etc.
Registers
·
This is a small memory unit on the CPU.
·
The data is stored here while it waits to be
processed. The ALU can then easily
·
access this data for its calculations. It helps
to easily and quickly get information stored in the computer memory.
·
It helps the CU to quickly transfer data to
other parts of the computer.
Do You Know?
The clock rate is the speed at
which a microprocessor executes instructions. Every computer contains an
internal clock that regulates the rate at which the instructions are executed.
The faster the clock, the more the instructions the CPU can execute per second.
The rough measure of the speed of the CPU in following instructions is measured
in MIPS (millions of instructions per second).
The Right Way
It is not advisable to open CPU
box without the help of a technical expert. Moreover, the parts inside it are
very delicate and sensitive.
The five major functions of a
computer system are input, storage, arithmetic and logic processing, output and
control. Different devices perform these specific functions.
The CPU controls, coordinates and
executes all instructions, and is therefore referred to as the brain of the
computer.
There are three main functional
units of the CPU: the Control Unit (CU), the Arithmetic Logic Unit (ALU) and
the Registers.
The CU is the supervisor of the
CPU and the whole computer.
The ALU performs all the
mathematical calculations and logical operations.
Registers is a small memory unit
on the CPU where all data to be processed is stored for easy and quick access
by the ALU.
Exercises
A. Tick (✔)
the correct option.
Which of the following is not a
function of computer?
(a) Controlling and coordinating ✔
(b) Making arithmetic calculations
(c) Thinking and deciding
Which of the following body
organs can CPU be compared to?
(a) Liver
(b) Brain ✔
(c) Backbone
What is the full form of VDU?
(a) Versatile Display Unit
(b) Visual Display Unit ✔
(c) Volatile Display Unit
Which among the following is the
odd one?
(a) ALU
(b) Keyboard ✔
(c) CU
B. Write the full form of each of the following:
CPU: Central Processing Unit
CU: Control Unit
ALU: Arithmetic Logic Unit
C. Fill in the blanks.
- Devices such as keyboard,
mouse, joystick and microphone are called input devices.
- The flow of information
between ALU and Registers is controlled by Control Unit (CU).
- The Arithmetic Logic Unit
(ALU) unit of CPU performs mathematical and logical operations.
- The instructions given as
input are first stored at storage unit before getting processed.
- In personal computers, CPU
is housed in a single chip called microprocessor.
D. Write the main functions of each of the following.
1. Central Processing Unit (CPU)
- Executes instructions of
computer programs.
- Performs basic arithmetic,
logical, and input/output operations.
- Controls the operation of
other computer components.
- Often referred to as the
"brain" of the computer.
2. Control Unit (CU)
- Coordinates and controls the
activities of all parts of the computer.
- Fetches instructions from
memory.
- Decodes instructions to
determine the required operations.
- Directs the flow of data
between the CPU, memory, and input/output devices.
3. Arithmetic Logic Unit (ALU)
- Performs arithmetic
operations (addition, subtraction, multiplication, division).
- Performs logical operations
(comparison, AND, OR, NOT).
- Supports data manipulation
and processing.
4. Registers
- Stores data temporarily for
quick access by the CPU.
- Holds intermediate results
of calculations.
- Stores addresses of memory
locations.
- Provides fast access to data
for the ALU and control unit.
F. Answer the following questions.
1. Why is CPU called the brain of the computer?
The CPU is called the brain of
the computer because it controls and processes all information.
2. What is the role of Registers in a CPU?
Registers in a CPU temporarily
store data for quick access during calculations
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