The Central Processing Unit:
What Goes on Inside the Computer
Chapter 3
CPU & It's Components
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The Central processing unit(CPU)
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What is CPU?
The computer does its primary work in a part of
the machine we cannot see, a control center that
converts data input to information output.
CPU: The entire processing unit of a computer,
responsible for executing instructions and
performing calculations.
CPU core: A single processing unit within a CPU,
capable of executing instructions independently.
Multiple cores within a CPU enable parallel
processing and improved multitasking.
This control center, called the central processing
unit (CPU), is a highly complex, extensive set of
electronic circuitry that executes stored program
instructions.
All computers, large and small, must have a central
processing unit.
Computers use two types of storage: Primary
storage and secondary storage. The CPU interacts
closely with primary storage, or main memory,
referring to it for both instructions and data
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How a CPU Works
The working of the CPU is defined
as a three-step process. First, an
instruction is fetched from
memory.
Second, the instruction is decoded
and the processor figures out what
it's being told to do.
Third, the instruction is executed
and an operation is performed.
These three steps repeat in a cycle
that begins again with the CPU
fetching the next instruction. The
steps are referred to as the
instruction cycle of the CPU.
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Components of the CPU
• The Control Unit
It contains circuitry that uses electrical signals to direct
the entire computer system to carry out, or execute,
stored program instructions
It does not process ,store or execute program
instructions; rather, it directs other parts of the system
to do so.
To transfer the data, it communicates with the input
and output devices and controls all the units of the
computer
It fetches the instructions from the main memory of a
processor and sent to the processor instruction
register, which contains register contents.
The control unit must communicate with both the
arithmetic/logic unit and memory
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The Arithmetic/Logic Unit
The ALU contains the electronic circuitry that
executes all arithmetic and logical operations.
The ALU can perform four kinds of arithmetic
operations, or mathematical calculations:
addition, subtraction, multiplication, and
division
It also performs logical operations, Such as
comparison.
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Arithmetic Operations
Addition
Subtraction
Multiplication
Division
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Logical Operations
• Evaluates conditions
• Makes comparisons
• Can compare
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Registers: Temporary Storage Areas
Registers are temporary storage areas for instructions or
data.
They are not a part of memory; rather they are special
additional storage locations that offer the advantage of
speed.
provides a fast way to collect and store data
If we want to manipulate data with a controller or
processor by performing addition, subtraction, and so
on, we cannot do that directly in the memory, but it
needs registers to process and store the data.
Registers work under the direction of the control unit to
accept, hold, and transfer instructions or data and
perform arithmetic or logical comparisons at high
speed. 9
Role of registry
An accumulator, which collects the result of
computations.
An address register, which keeps track of where a
given instruction or piece of data is stored in
memory. Each storage location in memory is
identified by an address, just as each house on a
street has an address.
A storage register, which temporarily holds data
taken from or about to be sent to memory.
A general-purpose register, which is used for
several functions.
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Memory
Memory is also known as primary storage,
primary memory, main storage, internal storage,
main memory, and RAM (Random Access
Memory)
Once the CPU converts a specific set of computer
program instructions into machine code, it stores
that machine code in primary storage or memory
Memory is the part of the computer that holds
data and instructions for processing
It stores program instructions or data for only as
long as the program they pertain to is in
operation
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Types of CPU
The major types of CPU are classified as:
single-core(oldest computer CPUs)-only focus on one operation at a
time so they were not very good at multi-tasking.
In Single Core CPU, FIFO (First Come First Serve) model is used
dual-core(multi-core CPUs)-contains two processors that can handle
multi-tasking much more easily, faster than single-core CPUs
Multi core processor is designed with using of various processing units
means “Cores” on one chip, and every core of processor is able to
perform their all tasks.
For example, if you are doing multiple activities at a same time like as using
WhatsApp and playing games then one core handles WhatsApp activities and other
core manage to another works such as game
Quad-core-is high power CPU, in which four different processors cores are
combined into one processor.
faster multitasking than dual-core CPUs. This does not mean that a single
task will be four times faster, but processing four tasks will be faster at a
time,
Read More:Hexa core, Octa-core, and Deca core processor
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CPU Usage
CPUs are also differentiated on the basis of their usage.
Since every device has different requirements, they also
need different CPUs for them.
Desktop CPUs: These are the CPUs that are used in daily
usage desktop computers. These CPUs have up to 32 CPU
cores or maybe more than that.
Laptop CPUs: These are the CPUs that are used in portable
laptops. These CPUs also include integrated graphics.
The CPUs made for laptops consume less power and
also generates less heat as compared to desktop
Server CPUs: These CPUs are used in all time working
servers. These CPUs can have huge numbers of CPU cores
up to 78 or more. Yet, these CPUs can also be used in
desktops.
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CPU Manufacture Companies
Intel: Intel has divided its CPUs in about 75 families.
Some of the famous Intel CPU families are
Core i3, Core i5, Celeron, Core i9, Core i7, Pentium,
Xeon, Atom
AMD: Similarly, AMD has also divided its CPUs in
about 58 families. Some of the famous AMD CPU
families are
Ryzen 3, A10, A12, Ryzen 5, Ryzen 7, Athlon, EPYC,
Opteron
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CPU Sockets and Slots
A processor inserts into a socket or slot,
depending on the model. Most
processors today insert into a socket.
The purpose of the motherboard
socket/slots to connect the processor to
the motherboard
Motherboard type must match processor
package
Types of sockets: Sockets are built around
pin grid or land grid arrays
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with pins aligned in uniform rows around the socket.
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with pins staggered over the socket to squeeze more pins into a small space
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