Introducing Computer System. Types of computers Types of Computers Desktop Computers Workstations...

26
Introducing Computer Introducing Computer System System

Transcript of Introducing Computer System. Types of computers Types of Computers Desktop Computers Workstations...

Introducing Computer Introducing Computer SystemSystem

Types of computersTypes of computers

Types of ComputersTypes of Computers Desktop Computers Desktop Computers WorkstationsWorkstations Notebook Computers Notebook Computers Tablet PCsTablet PCs Handheld PCsHandheld PCs Smart Phones Smart Phones

Computer: DefinitionComputer: Definition

A computer is a machine that can be programmed to A computer is a machine that can be programmed to manipulate symbols. manipulate symbols.

Its principal characteristics are:Its principal characteristics are:

1)1) It responds to a specific set of instructions in a well-It responds to a specific set of instructions in a well-defined manner. defined manner.

2)2) It can execute a prerecorded list of instructions (a It can execute a prerecorded list of instructions (a program). program).

3)3) It can quickly store and retrieve large amounts of It can quickly store and retrieve large amounts of datadata

Computer sizes and powerComputer sizes and power

Computers can be generally classified by size and power as Computers can be generally classified by size and power as follows, though there is considerable overlap:follows, though there is considerable overlap:

1)1) Personal computer: Personal computer: A small, single-user computer based on a A small, single-user computer based on a microprocessor. microprocessor.

2)2) Workstation: Workstation: A powerful, single-user computer. A workstation is A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor like a personal computer, but it has a more powerful microprocessor and, in general, a higher-quality monitorand, in general, a higher-quality monitor. .

3)3) Minicomputer: Minicomputer: A multi-user computer capable of supporting up to A multi-user computer capable of supporting up to hundreds of users simultaneouslyhundreds of users simultaneously. .

4)4) Mainframe: Mainframe: A powerful multi-user computer capable of supporting A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.many hundreds or thousands of users simultaneously.

5)5) Supercomputer: Supercomputer: An extremely fast computer that can perform An extremely fast computer that can perform hundreds of millions of instructions per secondhundreds of millions of instructions per second

All general-purpose computers require the following hardware All general-purpose computers require the following hardware components:components:

Central processing unit (Central processing unit (CPU):CPU): The heart of the computer, this is The heart of the computer, this is the component that actually executes instructions organized in the component that actually executes instructions organized in programs ("software") which tell the computer what to do. programs ("software") which tell the computer what to do.

Memory (fast, expensive, short-term memory):Memory (fast, expensive, short-term memory): Enables a Enables a computer to store, at least temporarily, data, programs, and computer to store, at least temporarily, data, programs, and intermediate results. intermediate results.

Mass storage device (slower, cheaper, long-term memory):Mass storage device (slower, cheaper, long-term memory): Allows a computer to permanently retain large amounts of data and Allows a computer to permanently retain large amounts of data and programs between jobs. Common mass storage devices include programs between jobs. Common mass storage devices include disk drives and tape drives. disk drives and tape drives.

Input device:Input device: Usually a keyboard and mouse, the input device is Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer. the conduit through which data and instructions enter a computer.

Output device:Output device: A display screen, printer, or other device that lets A display screen, printer, or other device that lets you see what the computer has accomplishedyou see what the computer has accomplished

SupercomputerSupercomputer A A supercomputersupercomputer is a is a computercomputer that is at the frontline of current that is at the frontline of current

processing capacity, particularly speed of calculation. processing capacity, particularly speed of calculation.

Supercomputers introduced in the 1960s were designed primarily by Supercomputers introduced in the 1960s were designed primarily by Seymour CraySeymour Cray at at Control Data CorporationControl Data Corporation (CDC), and led the (CDC), and led the market into the 1970s until Cray left to form his own company, market into the 1970s until Cray left to form his own company, Cray ResearchCray Research. .

He then took over the supercomputer market with his new designs, He then took over the supercomputer market with his new designs, holding the top spot in supercomputing for five years (1985–1990).holding the top spot in supercomputing for five years (1985–1990).

In the 1980s a large number of smaller competitors entered the In the 1980s a large number of smaller competitors entered the

market, in parallel to the creation of the market, in parallel to the creation of the minicomputerminicomputer market a market a decade earlier, but many of these disappeared in the mid-1990s decade earlier, but many of these disappeared in the mid-1990s "supercomputer market crash"supercomputer market crash".".

Supercomputer and MainframeSupercomputer and Mainframe

Supercomputer is a broad term for one of the fastest Supercomputer is a broad term for one of the fastest computers currently available. Supercomputers are very computers currently available. Supercomputers are very expensive and are employed for specialized applications expensive and are employed for specialized applications that require immense amounts of mathematical that require immense amounts of mathematical calculations (number crunching). For example, weather calculations (number crunching). For example, weather forecasting requires a supercomputer. Other uses of forecasting requires a supercomputer. Other uses of supercomputers scientific simulations, (animated) supercomputers scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting). Perhaps the data (e.g. in petrochemical prospecting). Perhaps the best known supercomputer manufacturer is Cray best known supercomputer manufacturer is Cray Research.Research.

  

MainframeMainframe Mainframe was a term originally referring to the cabinet containing Mainframe was a term originally referring to the cabinet containing

the central processor unit or "main frame" of a room-filling Stone the central processor unit or "main frame" of a room-filling Stone Age batch machine. After the emergence of smaller "minicomputer" Age batch machine. After the emergence of smaller "minicomputer" designs in the early 1970s, the traditional big iron machines were designs in the early 1970s, the traditional big iron machines were described as "mainframe computers" and eventually just as described as "mainframe computers" and eventually just as mainframes. Nowadays a Mainframe is a very large and expensive mainframes. Nowadays a Mainframe is a very large and expensive computer capable of supporting hundreds, or even thousands, of computer capable of supporting hundreds, or even thousands, of users simultaneously. The chief difference between a users simultaneously. The chief difference between a supercomputer and a mainframe is that a supercomputer channels supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs whereas a mainframe uses its power to execute many programs concurrently. In some ways, mainframes are more powerful than concurrently. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster programs. But supercomputers can execute a single program faster than a mainframe. The distinction between small mainframes and than a mainframe. The distinction between small mainframes and minicomputers is vague, depending really on how the manufacturer minicomputers is vague, depending really on how the manufacturer wants to market its machines.wants to market its machines.

Common usesCommon uses

used for highly calculation-intensive tasks such used for highly calculation-intensive tasks such as problems involving as problems involving

quantum mechanical physicsquantum mechanical physics,,weather forecastingweather forecasting, , climate research, climate research, physical simulations such as simulation of physical simulations such as simulation of

airplanes in airplanes in wind tunnelswind tunnels,, simulation of the detonation of simulation of the detonation of nuclear weaponsnuclear weapons

, and research into , and research into nuclear nuclear fusionfusion,,cryptanalysiscryptanalysis, , and many others.and many others.

WorkstationWorkstation

It is a type of computer used for engineering applications (CAD/CAM), It is a type of computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other types of applications desktop publishing, software development, and other types of applications that require a moderate amount of computing power and relatively high that require a moderate amount of computing power and relatively high quality graphics capabilities. quality graphics capabilities.

Workstations generally come with a large, high-resolution graphics screen, Workstations generally come with a large, high-resolution graphics screen, at large amount of RAM, built-in network support, and a graphical user at large amount of RAM, built-in network support, and a graphical user interface. interface.

Most workstations also have a mass storage device such as a disk drive, Most workstations also have a mass storage device such as a disk drive, but a special type of workstation, called a diskless workstation, comes but a special type of workstation, called a diskless workstation, comes without a disk drive. without a disk drive.

The most common operating systems for workstations are UNIX and The most common operating systems for workstations are UNIX and Windows NT. Windows NT.

Workstations are single-user computers. However, workstations are Workstations are single-user computers. However, workstations are typically linked together to form a local-area network, although they can also typically linked together to form a local-area network, although they can also be used as stand-alone systems. be used as stand-alone systems.

In networking, workstation refers to any computer connected to a local-area In networking, workstation refers to any computer connected to a local-area network. It could be a workstation or a personal computer. network. It could be a workstation or a personal computer.

  

Personal computerPersonal computer Personal computer:Personal computer: It can be defined as a small, relatively inexpensive It can be defined as a small, relatively inexpensive

computer designed for an individual user. computer designed for an individual user. In price, personal computers range anywhere from a few In price, personal computers range anywhere from a few

hundred pounds to over five thousand pounds. hundred pounds to over five thousand pounds. All are based on the microprocessor technology that All are based on the microprocessor technology that

enables manufacturers to put an entire CPU on one chip. enables manufacturers to put an entire CPU on one chip. Businesses use personal computers for word Businesses use personal computers for word

processing, accounting, desktop publishing, and for processing, accounting, desktop publishing, and for running spreadsheet and database management running spreadsheet and database management applications. applications.

At home, the most popular use for personal computers is At home, the most popular use for personal computers is for playing games and recently for surfing the Internet.for playing games and recently for surfing the Internet.

Personal computers first appeared in the late 1970s.Personal computers first appeared in the late 1970s. One of the first and most popular personal computers One of the first and most popular personal computers

was the Apple II, introduced in 1977 by Apple Computer. was the Apple II, introduced in 1977 by Apple Computer. During the late 1970s and early 1980s, new models and During the late 1970s and early 1980s, new models and

competing operating systems seemed to appear daily. competing operating systems seemed to appear daily. Then, in 1981, IBM entered the fray with its first personal Then, in 1981, IBM entered the fray with its first personal

computer, known as the IBM PC. computer, known as the IBM PC. The IBM PC quickly became the personal computer of The IBM PC quickly became the personal computer of

choice, and most other personal computer choice, and most other personal computer manufacturers fell by the wayside. P.C. is short for manufacturers fell by the wayside. P.C. is short for personal computer or IBM PC. personal computer or IBM PC.

Personal Computer Types Personal Computer Types Actual personal computers can be generally classified by size and Actual personal computers can be generally classified by size and

chassis / case.chassis / case. The chassis or case is the metal frame that serves as the structural The chassis or case is the metal frame that serves as the structural

support for electronic components.support for electronic components. Every computer system requires at least one chassis to house the Every computer system requires at least one chassis to house the

circuit boards and wiring. The chassis also contains slots for circuit boards and wiring. The chassis also contains slots for expansion boards. expansion boards.

If you want to insert more boards than there are slots, you will need If you want to insert more boards than there are slots, you will need an expansion chassis, which provides additional slots. an expansion chassis, which provides additional slots.

There are two basic flavors of chassis designs–desktop models and There are two basic flavors of chassis designs–desktop models and tower models–but there are many variations on these two basic tower models–but there are many variations on these two basic types. types.

Then come the portable computers that are computers small Then come the portable computers that are computers small enough to carry. Portable computers include notebook and enough to carry. Portable computers include notebook and subnotebook computers, hand-held computers, palmtops, and subnotebook computers, hand-held computers, palmtops, and PDAs.PDAs.

Arithmetic Logic UnitArithmetic Logic Unit

In In computingcomputing, an , an arithmetic logic unitarithmetic logic unit ( (ALUALU) is ) is a a digital circuitdigital circuit that performs that performs arithmeticarithmetic and and logicallogical operations. operations.

The ALU is a fundamental building block of the The ALU is a fundamental building block of the central processing unitcentral processing unit (CPU) of a computer, (CPU) of a computer, and even the simplest and even the simplest microprocessorsmicroprocessors contain contain one for purposes such as maintaining timers. one for purposes such as maintaining timers.

The processors found inside modern CPUs and The processors found inside modern CPUs and graphics processing units (graphics processing units (GPUsGPUs) accommodate ) accommodate very powerful and very complex ALUs; a single very powerful and very complex ALUs; a single component may contain a number of ALUs. component may contain a number of ALUs.

An ALU may also compare numbers and An ALU may also compare numbers and return return boolean truth valuesboolean truth values (true or false) (true or false) depending on whether one is equal to, depending on whether one is equal to, greater than or less than the other ("is 64 greater than or less than the other ("is 64 greater than 65?"). greater than 65?").

Logic operationsLogic operations

Logic operations involve Logic operations involve Boolean logicBoolean logic: : ANDAND, , OROR, , XORXOR NOTNOT. . These can be useful both for creating These can be useful both for creating

complicated complicated conditional statementsconditional statements and and processing processing boolean logicboolean logic..

Simple operations Simple operations

Most ALUs can perform the following operations:Most ALUs can perform the following operations: IntegerInteger arithmetic operations ( arithmetic operations (additionaddition, ,

subtractionsubtraction, and sometimes , and sometimes multiplicationmultiplication and and divisiondivision, though this is more expensive) , though this is more expensive)

Bitwise logic operationsBitwise logic operations ( (ANDAND, , NOTNOT, , OROR, , XORXOR) ) Bit-shiftingBit-shifting operations (shifting or rotating a word operations (shifting or rotating a word

by a specified number of bits to the left or right, by a specified number of bits to the left or right, with or without with or without sign extensionsign extension). Shifts can be ). Shifts can be interpreted as multiplications by 2 and divisions interpreted as multiplications by 2 and divisions by 2. by 2.

Inputs and outputsInputs and outputs

The inputs to the ALU are the data to be The inputs to the ALU are the data to be operated on (called operated on (called operandsoperands) and a code from ) and a code from the the control unitcontrol unit indicating which operation to indicating which operation to perform. Its output is the result of the perform. Its output is the result of the computation.computation.

In many designs the ALU also takes or In many designs the ALU also takes or generates as inputs or outputs a set of condition generates as inputs or outputs a set of condition codes from or to a codes from or to a status registerstatus register. These codes . These codes are used to indicate cases such as are used to indicate cases such as carrycarry-in or -in or carry-out, carry-out, overflowoverflow, , divide-by-zerodivide-by-zero, etc., etc.

Control unitControl unit

1)1) The control unit (often called a control system The control unit (often called a control system or central controller) manages the computer's or central controller) manages the computer's various components; various components;

2)2) it reads and interprets (decodes) the program it reads and interprets (decodes) the program instructions, instructions,

3)3) transforming them into a series of control transforming them into a series of control signals which activate other parts of the signals which activate other parts of the computer. computer.

4)4) A key component common to all CPUs is the A key component common to all CPUs is the program counterprogram counter, a special memory cell (a , a special memory cell (a registerregister) that keeps track of which location in ) that keeps track of which location in memory the next instruction is to be read from.memory the next instruction is to be read from.

The control system's functionThe control system's function The control system's function is as follows—note that this is a simplified The control system's function is as follows—note that this is a simplified

description, and some of these steps may be performed concurrently or in a description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:different order depending on the type of CPU:

Read the code for the next instruction from the cell indicated by the program Read the code for the next instruction from the cell indicated by the program counter. counter.

Decode the numerical code for the instruction into a set of commands or Decode the numerical code for the instruction into a set of commands or signals for each of the other systems. signals for each of the other systems.

Increment the program counter so it points to the next instruction. Increment the program counter so it points to the next instruction. Read whatever data the instruction requires from cells in memory (or Read whatever data the instruction requires from cells in memory (or

perhaps from an input device). The location of this required data is typically perhaps from an input device). The location of this required data is typically stored within the instruction code. stored within the instruction code.

Provide the necessary data to an ALU or register. Provide the necessary data to an ALU or register. If the instruction requires an ALU or specialized hardware to complete, If the instruction requires an ALU or specialized hardware to complete,

instruct the hardware to perform the requested operation. instruct the hardware to perform the requested operation. Write the result from the ALU back to a memory location or to a register or Write the result from the ALU back to a memory location or to a register or

perhaps an output device. perhaps an output device. Jump back to step (1). Jump back to step (1).

Memory hierarchy Memory hierarchy

The hierarchical arrangement of storage in The hierarchical arrangement of storage in current computer architectures is called current computer architectures is called the the memory hierarchymemory hierarchy. .

It is designed to take advantage of It is designed to take advantage of memory locality in computer programs. memory locality in computer programs.

Each level of the hierarchy has the Each level of the hierarchy has the properties of higher bandwidth, smaller properties of higher bandwidth, smaller size, and lower latency than lower levels.size, and lower latency than lower levels.

Categorizations of MemoryCategorizations of Memory On the basis of physical characteristics On the basis of physical characteristics a.a. Volatile/Non-volatileVolatile/Non-volatileb.b. Erasable/Non-ErasableErasable/Non-Erasable On the basis of various technique to design On the basis of various technique to design a.a. SemiconductorSemiconductorb.b. Magnetic MemoryMagnetic Memoryc.c. Optical MemoryOptical Memory On the basis of Access methodsOn the basis of Access methodsa.a. Random access memory Random access memory b.b. Sequential access memory Sequential access memory On the basis of locationOn the basis of locationa.a. Internal – Primary Internal – Primary b.b. External –Secondary External –Secondary

Volatile MemoryVolatile Memory Information is lost when power is switched Information is lost when power is switched

off . off .

Non-volatile MemoryNon-volatile Memory Information once stored is permanent Information once stored is permanent

      All RAM except the CMOS RAM used for the All RAM except the CMOS RAM used for the BIOS is volatile Memory that loses its contents BIOS is volatile Memory that loses its contents when the power is turned off. A computer's main when the power is turned off. A computer's main mem., made up of dynamic RAM or static RAM mem., made up of dynamic RAM or static RAM chips, loses its content immediately upon loss of chips, loses its content immediately upon loss of power. Contrast ROM, which is non-volatile power. Contrast ROM, which is non-volatile memory. memory.      Generally abbreviated as NVRAM, Non-     Generally abbreviated as NVRAM, Non-volatile memory is an area of data storage in the volatile memory is an area of data storage in the memory where data is not lost when the power memory where data is not lost when the power is turned off. Nonvolatile memory areas include is turned off. Nonvolatile memory areas include read-only memory (ROM) and flash memory read-only memory (ROM) and flash memory