Upload
varsha-sukhramani
View
223
Download
0
Embed Size (px)
Citation preview
8/8/2019 World of Computers
1/21
Presented By:-
Varsha. Sukhramani
Shabeen. Samnani
8/8/2019 World of Computers
2/21
Introduction
History of Computing
How Where Computers Introduces
Abacus Computers
Charles Babbage
Harvard Mark I
ENIAC Computers
Super Computers
Development of Computers
How Computers Work
8/8/2019 World of Computers
3/21
Acomputer is a machine which manipulates data according to a list of
instructions.
The first devices that resemble modern computers date to mid-20th
century(around 1940-1941). Early electronic computers were the size of a large
room, consuming as much power as several hundred modern personal
computers. Today, simple computers may be made small enough to fit into a
wrist watch and be powered from a watch battery. However, the most
common form of computer in use today is by far the embedded computer.
Embedded computers are small, simple devices that are often used to control
other devices.
Any computer with a certain minimum capability is, in principal, capable
of performing the same tasks that any other computer can perform.
8/8/2019 World of Computers
4/21
It is difficult to identify any one device as the earliest computer, partly because the
term "computer" has been subject to varying interpretations over time.Originally, the
term "computer" referred to a person who performed numerical calculations (a human
computer), often with the aid of a mechanical calculating device.. In 1801, Joseph
Marie Jacquard made an improvement to the textile loom that used a series of punchedpaper cards as a template to allow his loom to weave intricate patterns automatically.
In 1837, Charles Babbage was the first to conceptualize and design a fully
programmable mechanical computer that he called "TheAnalytical Engine".During the
first half of the 20th century, many scientific computing needs were met by increasingly
sophisticated analog computers, which used a direct mechanical or electrical model of
the problem as a basis for computation. However, these were not programmable and
generally lacked the versatility and accuracy of modern digital computers.Asuccession
of steadily more powerful and flexible computing devices were constructed in the 1930s
and 1940s, gradually adding the key features that are seen in modern computers
8/8/2019 World of Computers
5/21
The first to be demonstrated working was the Manchester Small-Scale Experimental Machine
(SSEM) ,while the technologies used in computers have changed dramatically since the first
electronic general-purpose computers of the 1940s.Vacuum tube-based computers were in use
throughout the 1950s, but were largely replaced in the 1960s, which were smaller, faster,
cheaper, used less power and were more reliable. By the 1970s, the adoption of integrated
circuit technology and the subsequent creation of microprocessors such as theIntel 4004 whichwere, speed, cost and reliability. The early and mid-1980s saw machines with a modest number
of vector processors working in parallel become the standard. Typical numbers of processors
were in the range of four to sixteen. By the 1980s, computers had become sufficiently small and
cheap to replace simple mechanical controls in domestic appliances such as washing machines.
Around the same time, computers became widely accessible for personal use by individuals in theform of home computers and the now ubiquitous personal computer. In the later 1980s and
1990s, attention turned from vector processors to massive parallel processing systems with
thousands of "ordinary" CPUs, some being off the shelf units and others being custom designs.
In conjunction with the widespread growth of theInternet since the 1990s, personal computers
are becoming as common as the television and the telephone and almost all modern electronicdevices contain a computer of some kind.
8/8/2019 World of Computers
6/21
The modern Abacus
The old Abacus
TheAbacus was an early aid for mathematical computations. Its only value is
that it aids the memory of the human performing the calculations. Askilled
abacus operator can work on addition and subtraction problems at the speedof a person equipped with a hand calculator (multiplication and division are
slower). The oldest survivingAbacus was used in 300bc, by the Babylonians.
TheAbacus is still an use today, principally in far east. AmodernAbacus
consists of rings that slide over rods but the older one dates from the time
when pebbles were used for counting. The modernAbacus is just therepresentation of the human fingers: the lower rings on each rod represent the
5 fingers and the 2 upper rings represent the 2 hands.
8/8/2019 World of Computers
7/21
Small section of the type of mechanism employed in Babbage's Difference Engine
By 1822 the English mathematician Charles Babbage was proposing a steam
driven calculating machine the size of a room, which he called the Difference
Engine. This machine would be able to compute tables of numbers, such aslogarithm tables. He obtained government funding for this project due to the
importance of numeric tables in ocean navigation.It was Babbage who made an important intellectual leap regarding the punched
cards. Babbage realized that punched paper could be employed as a storage
mechanism, holding computed numbers for future reference. Babbage called thetwo main parts of hisAnalytic Engine the "Store" and the "Mill", as both terms are
used in the weaving industry. The Store was where numbers were held and the
Mill was where they were "woven" into new results. In a modern computer these
same parts are called the memory unit and the central processing unit (CPU).
8/8/2019 World of Computers
8/21
The Harvard Mark I: an electro-mechanical computer
One early success was the Harvard MarkIcomputer which was built as a partnership
between Harvard andIBM in 1944. This was the first programmable digital computer
made in the U.S. But it was not a purely electronic computer. Instead the MarkIwas
constructed out of switches, relays, rotating shafts, and clutches.
One of the primary programmers for the MarkIwas a woman, Grace Hopper. Hopperfound the first computer "bug. The word "bug" had been used to describe a defect since
at least 1889 but Hopper is credited with coining the word "debugging" to describe the
work to eliminate program faults.
The MarkIoperated on numbers that were 23 digits wide. It could add or subtract
two of these numbers in three-tenths of a second, multiply them in four seconds, and
divide them in ten seconds. Forty-five years later computers could perform an addition
in a billionth of a second!. This kind of speed is obviously impossible for a machine
which must move a rotating shaft and that is why electronic computers killed off their
mechanical predecessors.
8/8/2019 World of Computers
9/21
"Electronic Numerical Integrator and Calculator"
The title of forefather of today's all-electronic digital computers is usually
awarded to ENIAC, which stood for Electronic NumericalIntegrator and
Calculator. ENIAC was built at the University of Pennsylvania between 1943and 1945 by two professors, John Mauchly and the 24 year old J. Presper
Eckert, . Like the MarkI, ENIAC employed paper card readers obtained from
IBM.
To perform this computation on ENIAC you had to rearrange a large number ofpatch cords and then locate three particular knobs on that vast wall of knobs
and set them to 3, 1, and 4.
One of the most obvious problems was that the design would require 18,000
vacuum tubes to all work simultaneously
8/8/2019 World of Computers
10/21
The Cray-2 was the world's fastest computer from 1985 to 1989.
Asupercomputer is a computer that is considered, or was considered at the time of
its introduction, to be at the frontline in terms of processing capacity, particularly
speed of calculation.
Supercomputers introduced in the 1960s were designed primarily by Seymour Cray
at Control Data Corporation (CDC), and led the market into the 1970s until Crayleft to form his own company, Cray Research. He then took over the supercomputer
market with his new designs, holding the top spot in supercomputing for five years
(19851990).
The term supercomputer itself is rather fluid, and today's supercomputer tends to
become tomorrow's normal computer. In the 1970s most supercomputers were
dedicated to running a vector processor, Today, parallel designs are based on "off the
shelf" server-class microprocessors, such as the PowerPC, Itanium, or x86-64, and
most modern supercomputers are now highly-tuned computer clusters using
commodity processors combined with custom interconnects.
8/8/2019 World of Computers
11/21
8/8/2019 World of Computers
12/21
As time progressed, people found they were using adding machines and slide rules toperform more and more extremely tedious calculations. Aiken, developed the MarkI
in 1944 to ease this calculating burden. During World WarII, researchers made
more advances to ease the burden of performing calculations. In 1946, they
developed the ENIA
C, Electronic NumericalIntegrator and Calculator. Thecomputer had 18,000 vacuum tubes which were used to perform calculations at a
rate of 5,000 additions per second.. In the next few years, a number of other "first
generation" computers were built. All of these early computers used vacuum tubes to
perform their calculations. In 1945, John von Neumann wrote a paper describing
how a binary program could be electronically stored in a computer .In 1947, theEDVAC, Electronic Discrete VariableAutomatic Computer, was built by Eckert
and Mauchley. In 1951, Eckert and Mauchley built the UNIVAC for use at the
Census Bureau. The UNIVAC used magnetic tape to store input/output rather
than the punch tape. In 1953, IBM continued to develop and expand its computer
line and within the next decade. Digital Equipped Computer
8/8/2019 World of Computers
13/21
Vanguard Motion AnalyzrSmall
In 1947, Bell Laboratories invented the transistor. This creation sparked the
production of a wave of "second generation" computers. By using transistors
in place of vacuum tubes, manufacturers could produce more reliable
computers. Using transistors was also less expensive than building acomputer with vacuum tubes. The combination of smaller size, better
reliability, and lower cost made these second generation computers very
popular with buyers. For scientists and engineers, large powerful computers
were built which were good at performing calculations. For banks andinsurance companies, computers which were smaller , faster and those which
were good at sorting and printing were built. Computer companies found
that it was expensive to produce two different lines of computers, so they set
to work to develop a computer which could perform both calculations and
data processing equally well.
8/8/2019 World of Computers
14/21
Vectral General Computer
In 1958, the first integrated circuit was made. This invention has led to the
widespread use of computers today. Scientists found a way to reduce the size
of transistors so they could place hundreds of them on a small silicon chip,
about a quarter of an inch on each side. This enabled computermanufacturers to build smaller computers. In 1956, FORTRAN, the first
programming language, was developed. The introduction of programming
languages enabled this third generation of computers to contain something
called an operating system.. Another aspect of new computing to the thirdgeneration machines was the presence of multiprogramming. It enabled the
computer to run a number of jobs simultaneously. The companies whomanufactured the third generation computers tried to create computers which
could successfully perform both calculations and sorts.
8/8/2019 World of Computers
15/21
Then, in 1971 Intel created the first microprocessor. The microprocessor was a
large-scale integrated circuit which contained thousands of transistors. In 1976,
Steve Jobs and Steve Wozniak built the firstApple computer in a garage in
California. Then, in 1981,IBM introduced its first personal computer. Thepersonal computer was such a revolutionary concept and was expected to have
such an impact on society that in 1982. Within a matter of years, computers
spread from the work place into the home. Personal computers have changed a
great deal since the early eighties. The hardware has definitely changed, the
computers are faster now, have more memory, The increased processing speed andmemory in computers has led to an increase in the quality of computer graphics.
The introduction of the integrated circuit and its development into the very-large
scale integrated circuit started a technological revolution which caused computers
to invade almost every aspect of our society.
8/8/2019 World of Computers
16/21
Control Unit
Memory
Input/output (I/O)
Arithmetic/Logic Unit (ALU)
8/8/2019 World of Computers
17/21
The control unit directs the various components of a computer. It reads and interprets
instructions in the program. Control systems in advanced computers may change theorder of some instructions so as to improve performance. Akey component common to
all CPUs is the program counter. The control system's function is as follows. Some of
these steps may be performed concurrently or in a different order depending on the type
of CPU:-
Read the code for the next instruction from the cell indicated by the program counter.Decode the numerical code for the instruction into a set of commands or signals for
each of the other systems.
Increment the program counter so it points to the next instruction.
Read whatever data the instruction requires from cells in memory. The location of
this required data is typically stored within the instruction code.Provide the necessary data to anALU or register.
If the instruction requires anALU or specialized hardware to complete, instruct the
hardware to perform the requested operation.
Write the result from theALU back to a memory location or to a register or perhaps
an output device.
8/8/2019 World of Computers
18/21
Magnetic Core Memory
Magnetic core memory was popular main memory for computers through the 1960suntil it was completely replaced by semiconductor memory.
Acomputer's memory can be viewed as a list of cells into which numbers can be placed
or read. The information stored in memory may represent practically anything. Letters,
numbers, even computer instructions. In almost all modern computers, each memory cell
is set up to store binary numbers in groups of eight bits (called a byte). Each byte is ableto represent 256 different numbers. Acomputer can store any kind of information in
memory as long as it can be somehow represented in numerical form. Computer main
memory comes in two principal varieties: random access memory or RAM and read-only
memory or ROM. ROM is pre-loaded with data and software that never changes. The
contents of RAM is erased when the power to the computer is turned off while ROM
retains its data indefinitely Software that is stored in ROM is often called firmware
because it is notionally more like hardware than software. Flash memory blurs the
distinction between ROM and RAM by retaining data when turned off but being
rewritable like RA
M.In more sophisticated computers there may be one or more R
AMcache memories which are slower than registers but faster than main memory.
8/8/2019 World of Computers
19/21
Common I/O Devices Used With Computers
Hard disks are CommonI/O devices used with computers.I/O is the means by
which a computer receives information from the outside world and sends results
back. Devices that provide input or output to the computer are called
peripherals. On a typical personal computer, peripherals include input deviceslike the keyboard and mouse, and output devices such as the display and printer.
Hard disk drives, floppy disk drives and optical disc drives serve as both input
and output devices. Computer networking is another form ofI/O.Often, I/O
devices are complex computers in their own right with their own CPU andmemory. Agraphics processing unit might contain fifty or more tiny computers
that perform the calculations necessary to display 3D graphics. Modern desktop
computers contain many smaller computers that assist the main CPU in
performingI/O.
8/8/2019 World of Computers
20/21
TheALU is capable of performing two classes of operations: arithmetic and
logic.The set of arithmetic operations that a particularALU supports may be
limited to adding and subtracting or might include multiplying or dividing.A
nycomputer can be programmed to perform any arithmetic operationalthough it
will take more time to do so if itsALU does not directly support the operation..
Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be
useful both for creating complicated conditional statements and processing
boolean logic.Superscalar computers contain multipleALUs so that they canprocess several instructions at the same time. Graphics processors and computers
with SIMD and MIMD features often provideALUs that can perform
arithmetic on vectors and matrices.
8/8/2019 World of Computers
21/21