2 computer hardware system

7/28/2019 2 Computer Hardware System

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Computer hardware is the physical part of a computer,

including the digital circuitry, as distinguished from the

computer software that executes within the hardware.

The hardware of a computer is infrequently changed, in

comparison with software and data, which are "soft" in

the sense that they are readily created, modified or

erased on the computer. Firmware is a special type of

software that rarely, if ever, needs to be changed and

so is stored on hardware devices such as read-onlymemory (ROM) where it is not readily changed (and is

therefore "firm" rather than just "soft").


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A. Input Hardware/Unit

1. TEXT DEVICESa peripheral modeled after the typewriter keyboard.

Keyboards are designed for the input of text and

characters, and also to control the operation of a

computer. Physically, computer keyboards are an

arrangement of rectangular or near-rectangular

buttons, or "keys". Keyboards typically havecharacters engraved or printed on the keys; in most

cases, each press of a key corresponds to a single

written symbol. However, to produce some symbols

requires pressing and holding several keys

simultaneously, or in sequence; other keys do notproduce any symbol, but instead affect the operation

of the computer, or the keyboard itself.


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2. Pointing Devices

MOUSE - is a handheld computer pointing device,designed to sit under one hand of the user and detectmovement relative to its supporting surface. Inaddition, it usually features buttons and/or otherdevices, such as "wheels", which allow performing

various system-dependent operations. TRACKBALL - pointing device consisting of a ball

housed in a socket containing sensors to detectrotation of the ball about two axeslike an upside-down mouse, but with the ball sticking out more. Theuser rolls the ball with their thumb, fingers, or thepalm of their hand to move a cursor.


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B. Processing Hardware

Unit

The computer you are using to read this pageuses a microprocessor to do its work. Themicroprocessor is the heart of any normalcomputer, whether it is a desktop machine, aserver or a laptop. The microprocessor mightbe a Pentium, a K6, a PowerPC, a Sparc orany of the many other brands and types of

microprocessors, but they all doapproximately the same thing inapproximately the same way.


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B. Processing Hardware Unit (Cont.)

A microprocessor -- also known as a CPU orcentral processing unit -- is a completecomputation engine that is fabricated on a singlechip. The first microprocessor was the Intel 4004,

introduced in 1971. The 4004 was not verypowerful -- all it could do was add and subtract,and it could only do that 4 bits at a time. But it wasamazing that everything was on one chip. Prior tothe 4004, engineers built computers either fromcollections of chips or from discrete components(transistors wired one at a time). The 4004powered one of the first portable electroniccalculators.


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B. Processing Hardware Unit (Cont.)

The first microprocessor to make it into a homecomputer was the Intel 8080, a complete 8-bitcomputer on one chip, introduced in 1974. The firstmicroprocessor to make a real splash in the marketwas the Intel 8088, introduced in 1979 and

incorporated into the IBM PC (which first appearedaround 1982). If you are familiar with the PC marketand its history, you know that the PC market movedfrom the 8088 to the 80286 to the 80386 to the 80486 tothe Pentium to the Pentium II to the Pentium III to the

Pentium 4. All of these microprocessors are made byIntel and all of them are improvements on the basicdesign of the 8088. The Pentium 4 can execute anypiece of code that ran on the original 8088, but it does

it about 5,000 times faster!


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Output Hardware Unit

1. Monitor(also known as computerscreen, or computer video display) - is adevice that can display signals generatedby a computer as images on a screen.(From the Latin verb moneo: to warn,advise.) There are many types ofmonitors, but they generally conform todisplay standards. Once an essentialcomponent of computer terminals,computer displays have long sincebecome standardised peripherals in theirown right.


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C. Output Hardware Unit (Cont.)

PRINTERS are devices that produce hard copy

(permanent human-readable text and/or graphics

of documents stored in electronic form, usually

on physical print media such as paper ortransparencies). Many printers are primarily used

as computer peripherals, and are permanently

attached to a computer which serves as a

document source.

- The world's first computer printer was a 19th-

century mechanically driven apparatus invented

by Charles Babbage for his Difference Engine.


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D. Storage Hardware Unit

Nearly every desktop computer andserver in use today contains one or morehard-disk drives. Every mainframe andsupercomputer is normally connected to

hundreds of them. You can even findVCR-type devices and camcorders thatuse hard disks instead of tape. Thesebillions of hard disks do one thing well --

they store changing digital information in arelatively permanent form. They givecomputers the ability to remember thingswhen the power goes out.


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D. Storage Hardware Unit (Con.t)

Hard disks were invented in the 1950s.They started as large disks up to 20inches in diameter holding just a fewmegabytes. They were originally called

"fixed disks" or "Winchesters" (a codename used for a popular IBM product).They later became known as "hard disks"to distinguish them from "floppy disks."

Hard disks have a hard platter that holdsthe magnetic medium, as opposed to theflexible plastic film found in tapes andfloppies.


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D. Storage Hardware Unit (Con.t)

At the simplest level, a hard disk is not

that different from a cassette tape. Both

hard disks and cassette tapes use the

same magnetic recording techniques

described in How Tape Recorders Work.Hard disks and cassette tapes also share

the major benefits of magnetic storage --

the magnetic medium can be easilyerased and rewritten, and it will

"remember" the magnetic flux patterns

stored onto the medium for many years.


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E. Other Input Devices GAMING

Joystick

often used to control games, and usuallyhave one or more push-buttons whose state canalso be read by the computer. Most I/O interfacecards for PCs have a joystick (game control) port.

Gamepad - A gamepad, also called joypad or control

pad, is a type of game controller held with bothhands where the thumbs are used to provide input.Gamepads generally feature a set of action buttonshandled with the right thumb and a directioncontroller handled with the left. The directioncontroller has traditionally been a four-way digital

cross (D-pad), but most modern controllersadditionally (or as a substitute) feature an analogstick.

Game Controller - an input device used to control avideo game


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E. Other Input Devices (Cont.)IMAGE/VIDEO:

Scanners - device that analyzes a physical image (such as aphotograph, printed text, or handwriting) or an object

(such as an ornament) and converts it to a digital image.

Webcam - is a real-time camera whose images can beaccessed using the World Wide Web, instant messaging,or a PC video calling application.

AUDIO:

Microphone - an acoustic to electric transducer thatconverts sound into an electrical signal.Microphones are used in many applications such astelephones, tape recorders, hearing aids, motionpicture production, live and recorded audioengineering, in radio and television broadcastingand in computers for recording voice, VoIP andnumerous other computer applications.


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E. Other Output Devices

Speakers - are external speakers and are usuallyequipped with a male-end phono plug for computer soundcards; however, there are some that have female RCA(phono) plug ports, and some people link computer soundcards to nearby stereo systems. There are also USB

speakers which gain their power from the 5 volts of a USBport. Computer speakers are usually a simplified stereosystem without a radio or other media sources built in.

Headsets - are a pair of transducers that receive anelectrical signal from a media player or receiver and usespeakers placed in close proximity to the ears (hence thename earphone) to convert the signal into audible soundwaves.


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F. History of Microprocessing

Chips

The introduction of the microprocessor in the 1970ssignificantly affected the design and implementationof CPUs. Since the introduction of the firstmicroprocessor (the Intel 4004) in 1970 and the firstwidely used microprocessor (the Intel 8080) in 1974,this class of CPUs has almost completely overtaken

all other central processing unit implementationmethods. Mainframe and minicomputer manufacturersof the time launched proprietary IC developmentprograms to upgrade their older computerarchitectures, and eventually produced instruction set

compatible microprocessors that were backward-compatible with their older hardware and software.Combined with the advent and eventual vast successof the now ubiquitous personal computer, the term"CPU" is now applied almost exclusively to

microprocessors.

F Hi f Mi i


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Chips(Cont.)

Previous generations of CPUs were implemented asdiscrete components and numerous small integratedcircuits (ICs) on one or more circuit boards.Microprocessors, on the other hand, are CPUsmanufactured on a very small number of ICs; usually justone. The overall smaller CPU size as a result of beingimplemented on a single die means faster switching timebecause of physical factors like decreased gate parasiticcapacitance. This has allowed synchronousmicroprocessors to have clock rates ranging from tens ofmegahertz to several gigahertz. Additionally, as the ability

to construct exceedingly small transistors on an IC hasincreased, the complexity and number of transistors in asingle CPU has increased dramatically. This widelyobserved trend is described by Moore's law, which hasproven to be a fairly accurate predictor of the growth of

CPU (and other IC) complexity to date.

F Hi t f Mi i


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Chips(Cont.)

While the complexity, size, construction, and general

form of CPUs have changed drastically over the

past sixty years, it is notable that the basic design

and function has not changed much at all. Almostall common CPUs today can be very accurately

described as Von Neumann stored-program

machines.

F Hi t f Mi i


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Chips(Cont.)

As the aforementioned Moore's law continues to hold true,

concerns have arisen about the limits of integrated circuit

transistor technology. Extreme miniaturization of electronic

gates is causing the effects of phenomena like

electromigration and subthreshold leakage to becomemuch more significant. These newer concerns are among

the many factors causing researchers to investigate new

methods of computing such as the quantum computer, as

well as to expand the usage of parallelism and other

methods that extend the usefulness of the classical Von

Neumann model.


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G. Secondary Storage

Technology

Floppy disk -a data storage device that iscomposed of a ring of thin, flexible (i.e. "floppy")

magnetic storage medium encased in a square or

rectangular plastic shell. Floppy disks are readand written by a floppy disk drive or FDD, the

latter initialism not to be confused with "fixed

disk drive", which is an old IBM term for a hard

disk drive.


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Technology (cont.)

CD-R - works by replacing the aluminum layer in

a normal CD with an organic dye compound. This

compound is normally reflective, but when the

laser focuses on a spot and heats it to a certaintemperature, it "burns" the dye, causing it to

darken. When you want to retrieve the data you

wrote to the CD-R, the laser moves back over the

disc and thinks that each burnt spot is a bump.The problem with this approach is that you can

only write data to a CD-R once. After the dye has

been burned in a spot, it cannot be changed back.


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Technology (cont.)

Flash memory - is a type of solid-state technology,

which basically means that there are no moving

parts. Inside the chip is a grid of columns and rows,

with a two-transistor cell at each intersecting point on

the grid.


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H. Block Diagram of a Typical

Computer System

The von Neumann (CISC) architecture employs a single bus.

CISC stands for Complex Instruction Set Computer. A single-

bus system is illustrated. The Harvard (RISC) architecture

utilizes two busses - a separate data bus and an address bus.

RISC stands for Reduced Instruction Set Computer.

Relationships are shown between the CPU, DRAM, local bus,

and the peripherals, which connect to the motherboard. The ISA

bus, SCSI Bus, PCI bus and USB Bus are shown. Some typical

PC parameters are given, along with a Graphics Resolutionchart.


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