Reedy (1984) quoted Aldous Huxleythus:‚that men do not learn very muchfrom the lessons of history is themost important of all the lessonsthat history has to teach.‛ This therefore emphasizes theneed to study history of the
A computer is any device which aids humans in performing various kinds of computations or calculations.In that respect the earliest computer was the abacus, used to perform basic arithmetic operations.Every computer supports some form of input, processing, and output.We input information, the computer processes it according to its basic
IntroductionThe word ‘computer’ is an old wordthat has changed its meaning severaltimes in the last few centuries. The American Heritage Dictionary (1980) gives its first computer definition as “a person who computes.” Webster’s Dictionary (1980) defines it as “a programmable electronic device that can store, retrieve, and process data”
Devices that comprise a Computer system Monitor Speaker (output) (output) System unit (processor, memory…) Printer (output) Storage devices (CD-RW, Floppy, Hard disk, zip,…) Mouse (input) Scanner Keyboard (input) (input) 6
Computers can perform four general operations, which comprise the information processing cycle. Input Process Output Storage 7
Computers can be classified according to their CAPACITY Volume of work or the data processing capability a computer can handle. PERFORMANCEData that can be Amount and type of Speed of softwarestored in memory Number and type internal available for use of peripheral operation devices
Modern computers do this electronically, which enables them to perform a vastly greater number of calculations or computations in less time.Graphics, sound etc. are merely abstractions of the numbers being crunched within the machine; in digital computers these are the ones and zeros, representing electrical on and off states, and endless combinations of those.In other words every image, every sound, and every word have a corresponding binary code.
HISTORYKonrad Zuse John Mauchly & J Eckert Sir Frederick Williams & Tom KilburnInventor of Modern Computer EINAC William Kilburn Tube - RAM 1939 1942 1946 1948 XXX XXX John von Newman Dr Eckert & John Mauchly John Atanasoff EINAC Modified UNIVAC Digital Computer
HISTORY OFCOMPUTERS First electronic computers used vacuum The second generation of computers tubes, and they were huge and complex. came about thanks to the invention of the transistor, which then started The first general purpose electronic replacing vacuum tubes in computer design. computer was the ENIAC (Electronic Numerical Integrator And Computer). The first transistor computer was created at the University of It was programmed using plugboards and Manchester in 1953 switches, supporting input from an IBM card reader, and output to an IBM card IBM also created the first disk drive punch. in 1956, the IBM 350 RAMAC It took up 167 square meters, weighed 27 tons, and consuming 150 kilowatts of Transistor computers consumed far power. It used thousands of vacuum tubes, less power, produced far less heat, crystal diodes, relays, resistors, and and were much smaller compared to capacitors. the first generation, albeit still big by today’s standards.
Third Fourth Generation Generation Computers (1960) Computers (1971) The invention of the integrated circuits First microchips-based central (ICs), also known as microchips, paved processing units consisted of multiple the way for computers as we know them microchips for different CPU today. components. Making circuits out of single pieces of silicon, which is a semiconductor, The drive for ever greater integration and allowed them to be much smaller and miniaturization led towards single-chip more practical to produce. CPUs, where all of the necessary CPU This also started the ongoing process of components were put onto a single integrating an ever larger number of microchip, called a microprocessor. transistors onto a single microchip. During the sixties microchips started The first single-chip CPU, or a making their way into computers, but microprocessor, was Intel 4004. the process was gradual, and second generation of computers still held on. The advent of the microprocessor Minicomputers can be seen as a bridge between mainframes and spawned the evolution of the microcomputers, which came later as the microcomputers, the kind that would proliferation of microchips in computers eventually become personal computers grew. that we are familiar with today.
First Generation ofMicrocomputers (1971 – 1976) First microcomputers often came in kits, and many were just boxes with lights and switches, usable only to engineers and hobbyists who could understand binary code. Some, however, did come with a keyboard and/or a monitor, bearing somewhat more resemblance to modern computers. The reason some might consider it a first microcomputer is because it could be used as a de-facto standalone computer, it was small enough, and its multi-chip CPU architecture actually became a basis for the x86 architecture later used in IBM PC and its descendants. However, if we are looking for the first microcomputer that came with a proper microprocessor, was meant to be a standalone computer, and didn’t come as a kit then it would be Micral N, which used Intel 8008 microprocessor.
Second GenerationMicrocomputers (1977) As microcomputers continued to evolve they became easier to operate, making them accessible to a larger audience. They typically came with a keyboard and a monitor, or could be easily connected to a TV, and they supported visual representation of text and numbers on the screen. Famous early examples of such computers include Commodore PET, Apple II, and in the 80s the IBM PC. The nature of the underlying electronic components didn’t change between these computers and modern computers we know of today, but what changed was the number of circuits that could be put onto a single microchip. Intel’s co-founder Gordon Moore predicted the doubling of the number of transistor on a single chip every two years, which became known as “Moore’s Law”, and this trend has roughly held for over 30 years .
MINICOMPUTERS In the 1960s, the growing demand for a smaller stand-alone machine brought about the manufacture of the minicomputer Minicomputer systems provide faster operating speeds and larger storage capacities than microcomputer systems Operating systems developed for minicomputer systems generally support both multiprogramming and virtual storage. 5Minicomputers usually have from 8k to 256k memory storage The PDP-8, the IBM systems 3 and the Honeywell 200 and 1200 computer are typical examples of minicomputers.
MEDIUM-SIZE COMPUTERS Medium-size computer systems provide faster operating speeds and larger storage capacities. They can support a large number of high-speed input/output devices and several disk drives. Medium-size computer can support a management information system. IBM System 370, Burroughs 3500 System and NCR Century 200 system are examples of medium-size computers. They usually have memory sizes ranging from 32k to 512k.
LARGE COMPUTERS Large computers are next to Super Computers and have bigger capacity than the Mediumsize computers. Large computers have storage capacities from 512k to 8192k. Expandability to 8 or even 16 million characters is possible with some of these systems. They are used in complex modeling, or simulation, business Operations, product testing, design and engineering work and in the development of space technology.
SUPERCOMPUTERSThe supercomputers are the biggest and fastest machines todayThese machines are applied in nuclear weapon development, accurate weather forecasting and as host processors for local computerSuper computers have capabilities far beyond even the traditional large-scale systemsSupercomputers may need the assistance of a medium-size general purpose machines (usually called front-end processor) to handle minor programs or perform slower speed or smaller volume operation.
Classification by their basicperating PRINCIPLE ANALOG DIGITAL HYBRID COMPUTERS COMPUTERS COMPUTERS
ANALOG COMPUTERSAnalog computers were well known in the 1940s they are now uncommon.In such machines, numbers to be used in some calculation were represented by physical quantities such as electrical voltages.The computing units of analog computers respond immediately to the changes which they detect in the input variables.Analog computers excel in solving differential equations and are faster than digital computers.
DIGITAL COMPUTERSMost computers today are digital. They represent information discretely and use a binary system.The Pocket Webster School & Office Dictionary (1990) simply defines Digital computers as “a computer using numbers in calculating.”They process data in numerical form and their circuits perform directly the mathematical operations of addition, subtraction, multiplication and division.Digital information is discrete, it can be copied exactly but it is difficult to make exact copies of analog information.
HYBRID COMPUTERSThese are machines that can work as both analog and digital computers.
Apple I, 1976Apple Computer was founded on April1, 1976 by a small group headed byJobs, engineer Steve Wozniak andindustry vet Ronald Wayne
Apple II, 1977The company hit the jackpot one year later with 1977s Apple II, a fully assembled desktop computer in a handsome case.Hackers still took to it because of its expandability. Schools used it to teach programming (it ran Integer BASIC) and offices started snatching them up once VisiCalc launched on the nascent platform.
Macintosh, 1984The Macintosh arrived in 1984, and it was the first computer to successfully integrate two things that are now commonplace: a graphical user interface and a mouse. Little pictures of folders, the piece of paper denoting a file, the trash can — most of us learned how all of these things worked when we sat down at the Mac.Apple launched the Macintosh with a massive media campaign spearheaded by a minute-long TV commercial (riffing on Orwells 1984) that aired during the Super Bowl.
Apple IIc, 1984 the Apple IIc, a slimmed-down version Apple released of the Apple II that was much more portable. It had a handle on the back so you could carry it around comfortably with one hand. It wasnt quite a laptop — the monitor and power supply werent attached — and the guts werent a whole lot different than what you got in the bigger Apple II models. It was one of the first small-form-factor PCs to hit the market, signaling the industry-wide move toward compact. It was an era when computers beginning to creep into middle-class homes, and first-time buyers found the IIc a "friendly" and appealing option. It looked equally attractive in the family room as it did in the office.
LaserWriter, 1985 The LaserWriter wasnt the first desktop laser printer to hit the market, but it was the first created for the Macintosh, and the first to use the cutting-edge PostScript language It was announced on the same day as its killer app, Aldus PageMaker. the LaserWriter wasnt the first shot fired in the desktop publishing revolution, it was the first to draw blood as it costs $7,000.
Pixar, 1986 Steve Jobs bought Pixar in 1986.Jobs paid $5 million to George Lucas and sank $5 million of his own money into the company. His original vision for Pixar was to develop graphics- rendering hardware and software, but the business eventually evolved into an animation studio. Jobs signed a distribution deal with Disney and Pixar began cranking out a string of hit family films, all of them computer-animated. 1995s Toy Story was the first blockbuster. Toy Story 2, Monsters, Inc., Finding Nemo, The Incredibles, Cars, WALL-E and Upfollowed. Accolades and Oscars came rolling in, along with massive mountains of cash. In 2006, Jobs flipped his original $10 million investment, selling Pixar to Disney for $7.4 billion in stock.
NeXT, 1988 After the success of the Macintosh, Jobs was marginalized by Apples board of directors, so he left to found a new computer company called NeXT. Jobs launched a new computer system at NeXT. Its most famous workstation was an austere black cube that cost $6,500. It ran a new operating system, NeXTSTEP, which was based on Unix. It was fast and especially adept at math functions, and it had a built-in Ethernet port in an age when most computers still needed a network interface card. Tim Berners-Lee used one to write the first web server and the first web browser. The first server node on the World Wide Web was a NeXT box.
iMac, 1998After NeXT failed to gain traction, Jobs sold the company to Apple and came back into the fold in 1996.Two years later, the company released a complete rewrite of the desktop PC — the candy-colored iMac.The first iMac was a runaway hit, and the all-in-one design is still used by todays iMac (and widely copied by other PC manufacturers).
Power Mac G4 Cube, 2000Jobs wasnt ready to let go of his dream of a cube-shaped computer, which he first tried at NeXT.He encouraged Apple designer Jonathan Ive to work the shape into the Power Mac line, and the company pumped out the eight-inch clear acrylic cube in 2000.It didnt do so hot. It was $1,800, the disk drive had problems, and the case developed stress cracks easily.
iPod, 2001The first iPod was a $400 MP3 player with a 5- gigabyte hard drive and a mechanical scroll wheel that didnt sync to Windows machines.The iPods all-white design was minimalist compared to other players that came before and, more importantly, the user interface was remarkably easy for anyone who picked it up to figure out.The hardware had its quirks — if you got sand in the scroll wheel, youd get stuck listening to Spin Doctors all day the touch-wheel, a color screen for watching videos and eventually, the industry-standard touchscreen.