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Computer Hardware

Ministry of Higher EducationBamyan University

Computer Science Department

Presented by : Mustafa Kamel MohammadiEmail : bamian.cs@gmail.com

Microprocessor

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learning objective In this chapter you will learn and answer to the following questions

What is a transistor? What is an IC? How CPU is made? Components of CPU CPU cooling system

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Introduction to Microprocessor• Also called CPU ( Central processing unit)• Consists of several parts, that together carry out all instructions and actions• Microprocessor is made of millions of microscopic transistor• Constructed from semiconductor silicon electric circuits• Semiconductor material is neither a conductor nor insulator but can chemically

be altered to be either one.• Silicon is conductor whenever combined with phosphorus however it can be insulator when

combined with baron.

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Transistor• Primary circuits used in microprocessors• Used in different ways but the basic function is to store an electric voltage that

shows a bit.• Something like an electric light switch• Microprocessors contain million to billions of transistors• The more transistors the better computing power• Amount of electric power stored in transistors are not very high• Older ones 5 volt and newer 2.2 volt• Stores data by switching between low and high voltage• 2.2 v transistor increased performance and decreased heat generated by CPU.

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IC ( Integrated Circuits)• An integrated circuit (IC) is a combination of electronic components, such as

transistors, capacitors, and resistors.• Designed to fulfill some logical function• Can be built to be a timer, counter, a bank of computer memory or even a

microprocessor.• The basic building block of an IC is a logic gate• A logic gate performs the Boolean algebra AND operation by testing two input

signals.

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Microprocessors• Is a multifunction IC (integrated circuits)• Made up of several parts• Primary parts of CPU are:• CU ( Control Unit)

• Controls the functions carried out in CPU• It tell the parts of CPU, what data to use, how should be operated and where to store result• Acts like a manager

• PTU (Protection Test Unit)• Works with the control unit to monitor whether or not functions are carried out correctly• It is like the quality control department of the CPU• If it detects something is not done properly, it generates an error signal.

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Cont.• Arithmetic and Logic Unit (ALU)

• ALU performs all of the calculations and comparative logic functions for the CPU, including all add, subtract, divide, multiply, equal to, greater than, less than, and other arithmetic and logic operations

• Floating Point Unit (FPU) • Also called math coprocessor, the numerical processing unit (NPU), and the numerical data

processor (NDP).• Handles all floating point operations for the ALU and CU• Involve arithmetic on numbers with decimal places and high math operations like

trigonometry and logarithms

• Memory Management Unit (MMU)• The MMU handles the addressing and cataloging of where data is stored in system memory• Whenever the CPU needs something from memory, it requests it from the MMU

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Cont.• Bus Interface Unit (BIU)

• Supervises the transfer of data over the bus system between the other components of the computer and the CPU.

• The Pre-fetch Unit• Preloads the instruction registers of the CPU with instructions from memory whenever BIU is

idle.• This allows the CPU to look ahead at future instructions

• Decode Unit• Many instructions are actually combinations of simpler instructions• Decodes incoming instructions to their simplest form• While the pre-fetch unit retrieving more instructions, this unit decodes them to get them

ready for the control unit

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Cont.• Registers

• Built into the CPU are a number of holding areas and buffers that are used to temporarily hold the • data, addresses, and instructions

• Being passed around between the CPU’s components.

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CPU’s bus system• Various bus to transfer information

• Data bus• Address bus• Control bus

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CPU’s cooling system• Early processors were cooled by airflow created in case by Power supply fan• Then processors were cooled by CPU heat sink or CPU fan.• Processor is not the only high-heat generating device inside the computer case

but also• accelerated video cards and high-speed hard disk drives

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References• “PC hardware a beginner’s guide” by Ron gilster• “PC architecture by Michael Karbo” 2005• “Illustrated guide to PC hardware” by Michael karbo 1998