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Processing Device
A CPU (Central Processing Unit) is also known as the Brain of a Computer. As it appears, it is a hardware
component, but it is also an important functional component of a computer system. It does all the
processing, calculations and comparisons at a rapid speed. Its speed is
measured in higher units of Hertz (Hz), such as 9 MHz. It takes information
from the input unit or memory and processes it as per the given instructions.
Processing includes calculations, comparisons, decision making, etc.
Some versions of processors are Pentium series, Dual Core, Core 2 Duo, Athlon,
IBM Cyrix, Core-i3, Core-i5, Core-i7, AMD FX Series, etc.
Functional Elements of a CPU
The functional elements of a CPU can be divided into three parts:
l Arithmetic Logic Unit (ALU)
l Control Unit (CU)
l Memory Unit (MU)
INSTRUCTIONS
CONTROL UNIT (CU)
MEMORY UNIT (MU) INPUT/OUTPUT UNIT
ARITHMETIC LOGIC
UNIT (ALU) DATA
Arithmetic Logic Unit (ALU)
An ALU performs mathematical calculations (addition, subtraction, multiplication, division, etc.) and
logical comparisons (greater than(>), less than(<), equal to (=), not equal to(!=), etc.). Logical Operation
refers to a comparison between two phrases that results in TRUE or FALSE value. It receives the coded
data and manipulates them to produce information in machine code and then send to the control unit.
Control Unit (CU)
A control unit co-ordinates and directs the operation of the hardware devices. It also co-ordinates the
flow and execution of the data and instructions, that are fed into the computer’s memory. CU functions in
a F-D-E-S (Fetch-Decode-Execute-Store) cycle. It fetches the instruction and data from the memory unit
and decodes them and passes them to the ALU for further processing. It also directs the ALU to execute
the instructions and performs the required operations on the data.
Memory Unit (MU)
A memory unit or main storage or the internal storage stores the data, instructions, intermediate and the
final results that are ready for the output. All instructions or data are stored in the memory unit before
being used by the ALU or the CU.
18 Touchpad Computer Applications (Ver. 2.0)-IX

