YABA COLLEGE OF TECHNOLOGY

SCHOOL OF ART, DESIGN AND PRINTING

DEPARTMENT OF PHOTOGRAPHY

Name :JEGEDE ADEDEJI SOLOMON

COURSE CODE: COM 101

COURSE TITLE: COMPUTER

TOPIC : HISTORY OF COMPUTER

A computer might be described with deceptive simplicity as “an apparatus that performs rou
tine calculations automatically.” Such a definition would owe its deceptiveness to a naive an
d narrow view of calculation as a strictly mathematical process. In fact, calculation underlies
many activities that are not normally thought of as mathematical. Walking across a room, for
instance, requires many complex, albeit subconscious, calculations. Computers, too, have pr
oved capable of solving a vast array of problems, from balancing a check book to even—in th
e form of guidance systems for robots—walking across a room.

Before the true power of computing could be realized, therefore, the naive view of calculatio
n had to be overcome. The inventors who laboured to bring the computer into the world ha
d to learn that the thing they were inventing was not just a number cruncher, not merely a c
alculator. For example, they had to learn that it was not necessary to invent a new computer
for every new calculation and that a computer could be designed to solve numerous proble
ms, even problems not yet imagined when the computer was built. They also had to learn ho
w to tell such a general problem-solving computer what problem to solve. In other words, th
ey had to invent programming.

They had to solve all the heady problems of developing such a device, of implementing the d
esign, of actually building the thing. The history of the solving of these problems is the histor
y of the computer. That history is covered in this section, and links are provided to entries on
many of the individuals and companies mentioned. In addition, see the articles computer sci
ence and supercomputer.

Early history

Computer precursors

The abacus

The earliest known calculating device is probably the abacus. It dates back at least to 1100 b
ce and is still in use today, particularly in Asia. Now, as then, it typically consists of a rectangu
lar frame with thin parallel rods strung with beads. Long before any systematic positional not
ation was adopted for the writing of numbers, the abacus assigned different units, or weight
s, to each rod. This scheme allowed a wide range of numbers to be represented by just a few
beads and, together with the invention of zero in India, may have inspired the invention of t
he Hindu-Arabic number system. In any case, abacus beads can be readily manipulated to pe
rform the common arithmetical operations—addition, subtraction, multiplication, and divisi
on—that are useful for commercial transactions and in bookkeeping.

The abacus is a digital device; that is, it represents values discretely. A bead is either in one p
redefined position or another, representing unambiguously, say, one or zero.

Analog calculators: from Napier’s logarithms to the slide rule

Calculating devices took a different turn when John Napier, a Scottish mathematician, publis
hed his discovery of logarithms in 1614. As any person can attest, adding two 10-digit numbe
rs is much simpler than multiplying them together, and the transformation of a multiplicatio
n problem into an addition problem is exactly what logarithms enable. This simplification is p
ossible because of the following logarithmic property: the logarithm of the product of two n
umbers is equal to the sum of the logarithms of the numbers. By 1624, tables with 14 signific
ant digits were available for the logarithms of numbers from 1 to 20,000, and scientists quick
ly adopted the new labour - saving tool for tedious astronomical calculations.

Most significant for the development of computing, the transformation of multiplication into
addition greatly simplified the possibility of mechanization. Analog calculating devices based
on Napier’s logarithms—representing digital values with analogous physical lengths—soon a
ppeared. In 1620 Edmund Gunter, the English mathematician who coined the terms cosine a
nd cotangent, built a device for performing navigational calculations: the Gunter scale, or, as
navigators simply called it, the gunter. About 1632 an English clergyman and mathematician
named William Oughtred built the first slide rule, drawing on Napier’s ideas. That first slide r
ule was circular, but oughtred also built the first rectangular one in 1633. The analoge device
s of Gunter and oughtred had various advantages and disadvantages compared with digital d
evices such as the abacus. What is important is that the consequences of these design decisi
ons were being tested in the real world.

Digital calculators: from the Calculating Clock to the Arithmometer

Calculating Clock A reproduction of Wilhelm Schickard's Calculating Clock. The device could
add and subtract six-digit numbers (with a bell for seven-digit overflows) through six interloc
king gears, each of which turned one-tenth of a rotation for each full rotation of the gear to i
ts right. Thus, 10 rotations of any gear would produce a “carry” of one digit on the following
gear and change the corresponding display.(more)

In 1623 the German astronomer and mathematician Wilhelm Schickard built the first calcula
tor. He described it in a letter to his friend the astronomer Johannes Kepler, and in 1624 he
wrote again to explain that a machine he had commissioned to be built for Kepler was, appa
rently along with the prototype, destroyed in a fire. He called it a Calculating Clock, which m
odern engineers have been able to reproduce from details in his letters. Even general knowle
dge of the clock had been temporarily lost when Schickard and his entire family perished dur
ing the Thirty Years’ War.

But Schickard may not have been the true inventor of the calculator. A century earlier, Leona
rdo da Vinci sketched plans for a calculator that were sufficiently complete and correct for m
odern engineers to build a calculator on their basis.

Arithmetic Machine, or Pascaline The Arithmetic Machine, or Pascaline, a French monetary

(non decimal) calculator designed by Blaise Pascal c. 1642. Numbers could be added by turni
ng the wheels (located along the bottom of the machine) clockwise and subtracted by turnin
g the wheels counterclockwise. Each digit in the answer was displayed in a separate window,
visible at the top of the photograph.(more)

The first calculator or adding machine to be produced in any quantity and actually used was
the Pascaline, or Arithmetic Machine, designed and built by the French mathematician-philo
sopher Blaise Pascal between 1642 and 1644. It could only do addition and subtraction, with
numbers being entered by manipulating its dials. Pascal invented the machine for his father,
a tax collector, so it was the first business machine too (if one does not count the abacus). H
e built 50 of them over the next 10 years.
Step Reckoner A reproduction of Gottfried Wilhelm von Leibniz's Step Reckoner, from the ori
ginal located in the Trinks Brunsviga Museum at Hannover, Germany. Turning the crank (left)
rotated several drums, each of which turned a gear connected to a digital counter.(more)

In 1671 the German mathematician-philosopher Gottfried Wilhelm von Leibniz designed a c

alculating machine called the Step Reckoner. (It was first built in 1673.) The Step Reckoner ex
panded on Pascal’s ideas and did multiplication by repeated addition and shifting.

Leibniz was a strong advocate of the binary number system. Binary numbers are ideal for ma
chines because they require only two digits, which can easily be represented by the on and o
ff states of a switch. When computers became electronic, the binary system was particularly
appropriate because an electrical circuit is either on or off. This meant that on could represe
nt true, off could represent false, and the flow of current would directly represent the flow o
f logic.

Leibniz was prescient in seeing the appropriateness of the binary system in calculating machi
nes, but his machine did not use it. Instead, the Step Reckoner represented numbers in deci
mal form, as positions on 10-position dials. Even decimal representation was not a given: in
1668 Samuel Morland invented an adding machine specialized for British money—a decidedl
y non decimal system.

Pascal’s, Leibniz’s, and Morland’s devices were curiosities, but with the Industrial Revolution
of the 18th century came a widespread need to perform repetitive operations efficiently. Wit
h other activities being mechanized, why not calculation? In 1820 Charles Xavier Thomas de
Colmar of France effectively met this challenge when he built his Arithmometer, the first co
mmercial mass-produced calculating device. It could perform addition, subtraction, multiplic
ation, and, with some more elaborate user involvement, division. Based on Leibniz’s technol
ogy, it was extremely popular and sold for 90 years. In contrast to the modern calculator’s cr
edit-card size, the Arithmometer was large enough to cover a desktop.

The Jacquard loom

Calculators such as the Arithmometer remained a fascination after 1820, and their potential
for commercial use was well understood. Many other mechanical devices built during the 19
th century also performed repetitive functions more or less automatically, but few had any a
pplication to computing. There was one major exception: the Jacquard loom, invented in 180
4–05 by a French weaver, Joseph-Marie Jacquard.
Jacquard loom Jacquard loom, engraving, 1874. At the top of the machine is a stack of punc
hed cards that would be fed into the loom to control the weaving pattern. This method of au
tomatically issuing machine instructions was employed by computers well into the 20th cent
ury.(more)

The Jacquard loom was a marvel of the Industrial Revolution. A textile-weaving loom, it coul
d also be called the first practical information-processing device. The loom worked by tuggin
g various-coloured threads into patterns by means of an array of rods. By inserting a card pu
nched with holes, an operator could control the motion of the rods and thereby alter the pa
ttern of the weave. Moreover, the loom was equipped with a card-reading device that slippe
d a new card from a pre-punched deck into place every time the shuttle was thrown, so that
complex weaving patterns could be automated.

What was extraordinary about the device was that it transferred the design process from a l
abour-intensive weaving stage to a card-punching stage. Once the cards had been punched a
nd assembled, the design was complete, and the loom implemented the design automaticall
y. The Jacquard loom, therefore, could be said to be programmed for different patterns by th
ese decks of punched cards.

For those intent on mechanizing calculations, the Jacquard loom provided important lessons:
the sequence of operations that a machine performs could be controlled to make the machi
ne do something quite different; a punched card could be used as a medium for directing th
e machine; and, most important, a device could be directed to perform different tasks by fee
ding it instructions in a sort of language—i.e., making the machine programmable.

It is not too great a stretch to say that, in the Jacquard loom, programming was invented bef
ore the computer. The close relationship between the device and the program became appa
rent some 20 years later, with Charles Babbage’s invention of the first computer.

The first computer

By the second decade of the 19th century, a number of ideas necessary for the invention of t
he computer were in the air. First, the potential benefits to science and industry of being abl
e to automate routine calculations were appreciated, as they had not been a century earlier.
Specific methods to make automated calculation more practical, such as doing multiplication
by adding logarithms or by repeating addition, had been invented, and experience with bot
h analog and digital devices had shown some of the benefits of each approach. The Jacquard
loom (as described in the previous section, Computer precursors) had shown the benefits of
directing a multipurpose device through coded instructions, and it had demonstrated how p
unched cards could be used to modify those instructions quickly and flexibly. It was a mathe
matical genius in England who began to put all these pieces together.

The Difference Engine

Difference Engine The completed portion of Charles Babbage's Difference Engine, 1832. This
advanced calculator was intended to produce logarithm tables used in navigation. The value
of numbers was represented by the positions of the toothed wheels marked with decimal nu
mbers.(more)

Charles Babbage was an English mathematician and inventor: he invented the cowcatcher, re
formed the British postal system, and was a pioneer in the fields of operations research and
actuarial science. It was Babbage who first suggested that the weather of years past could be
read from tree rings. He also had a lifelong fascination with keys, ciphers, and mechanical do
lls.

As a founding member of the Royal Astronomical Society, Babbage had seen a clear need to
design and build a mechanical device that could automate long, tedious astronomical calcula
tions. He began by writing a letter in 1822 to Sir Humphry Davy, president of the Royal Societ
y, about the possibility of automating the construction of mathematical tables—specifically, l
ogarithm tables for use in navigation. He then wrote a paper, “On the Theoretical Principles
of the Machinery for Calculating Tables,” which he read to the society later that year. (It won
the Royal Society’s first Gold Medal in 1823.) Tables then in use often contained errors, whic
h could be a life-and-death matter for sailors at sea, and Babbage argued that, by automatin
g the production of the tables, he could assure their accuracy. Having gained support in the s
ociety for his Difference Engine, as he called it, Babbage next turned to the British governme
nt to fund development, obtaining one of the world’s first government grants for research an
d technological development.

Babbage approached the project very seriously: he hired a master machinist, set up a firepro
of workshop, and built a dustproof environment for testing the device. Up until then calcula
tions were rarely carried out to more than 6 digits; Babbage planned to produce 20- or 30-di
git results routinely. The Difference Engine was a digital device: it operated on discrete digits
rather than smooth quantities, and the digits were decimal (0–9), represented by positions o
n toothed wheels, rather than the binary digits that Leibniz favored (but did not use). When
one of the toothed wheels turned from 9 to 0, it caused the next wheel to advance one posi
tion, carrying the digit just as Leibniz’s Step Reckoner calculator had operated.

The Difference Engine was more than a simple calculator, however. It mechanized not just a s
ingle calculation but a whole series of calculations on a number of variables to solve a compl
ex problem. It went far beyond calculators in other ways as well. Like modern computers, th
e Difference Engine had storage—that is, a place where data could be held temporarily for la
ter processing—and it was designed to stamp its output into soft metal, which could later be
used to produce a printing plate.

Nevertheless, the Difference Engine performed only one operation. The operator would set
up all of its data registers with the original data, and then the single operation would be repe
atedly applied to all of the registers, ultimately producing a solution. Still, in complexity and
audacity of design, it dwarfed any calculating device then in existence.

The full engine, designed to be room-size, was never built, at least not by Babbage. Although
he sporadically received several government grants—governments changed, funding often r
an out, and he had to personally bear some of the financial costs—he was working at or nea
r the tolerances of the construction methods of the day, and he ran into numerous construc
tion difficulties. All design and construction ceased in 1833, when Joseph Clement, the mach
inist responsible for actually building the machine, refused to continue unless he was prepai
d. (The completed portion of the Difference Engine is on permanent exhibition at the Scienc
e Museum in London.)

The Analytical Engine

Charles Babbage: Analytical Engine A portion (completed 1910) of Charles Babbage's Analy
tical Engine. Only partially built at the time of his death in 1871, this portion contains the “m
ill” (functionally analogous to a modern computer's central processing unit) and a printing m
echanism.(more)

While working on the Difference Engine, Babbage began to imagine ways to improve it. Chie
fly he thought about generalizing its operation so that it could perform other kinds of calcula
tions. By the time the funding had run out in 1833, he had conceived of something far more
revolutionary: a general-purpose computing machine called the Analytical Engine.

The Analytical Engine was to be a general-purpose, fully program-controlled, automatic mec

hanical digital computer. It would be able to perform any calculation set before it. Before Ba
bbage there is no evidence that anyone had ever conceived of such a device, let alone attem
pted to build one. The machine was designed to consist of four components: the mill, the sto
re, the reader, and the printer. These components are the essential components of every co
mputer today. The mill was the calculating unit, analogous to the central processing unit (CP
U) in a modern computer; the store was where data were held prior to processing, exactly a
nalogous to memory and storage in today’s computers; and the reader and printer were the
input and output devices.

As with the Difference Engine, the project was far more complex than anything theretofore b
uilt. The store was to be large enough to hold 1,000 50-digit numbers; this was larger than th
e storage capacity of any computer built before 1960. The machine was to be steam-driven a
nd run by one attendant. The printing capability was also ambitious, as it had been for the Di
fference Engine: Babbage wanted to automate the process as much as possible, right up to p
roducing printed tables of numbers.

The reader was another new feature of the Analytical Engine. Data (numbers) were to be ent
ered on punched cards, using the card-reading technology of the Jacquard loom. Instruction
s were also to be entered on cards, another idea taken directly from Jacquard. The use of ins
truction cards would make it a programmable device and far more flexible than any machine
then in existence. Another element of programmability was to be its ability to execute instru
ctions in other than sequential order. It was to have a kind of decision-making ability in its co
nditional control transfer, also known as conditional branching, whereby it would be able to j
ump to a different instruction depending on the value of some data. This extremely powerful
feature was missing in many of the early computers of the 20th century.

By most definitions, the Analytical Engine was a real computer as understood today—or wou
ld have been, had not Babbage run into implementation problems again. Actually building hi
s ambitious design was judged infeasible given the current technology, and Babbage’s failure
to generate the promised mathematical tables with his Difference Engine had dampened ent
husiasm for further government funding. Indeed, it was apparent to the British government
that Babbage was more interested in innovation than in constructing tables.

All the same, Babbage’s Analytical Engine was something new under the sun. Its most revolu
tionary feature was the ability to change its operation by changing the instructions on punch
ed cards. Until this breakthrough, all the mechanical aids to calculation were merely calculat
ors or, like the Difference Engine, glorified calculators. The Analytical Engine, although not ac
tually completed, was the first machine that deserved to be called a computer.

Ada Lovelace, the first programmer

Ada Lovelace Portrait of Ada Lovelace by Margaret Carpenter, 1836.

The distinction between calculator and computer, although clear to Babbage, was not appar
ent to most people in the early 19th century, even to the intellectually adventuresome visito
rs at Babbage’s soirees—with the exception of a young girl of unusual parentage and educati
on.

Ada Lovelace's life and impact on scientific computing Walter Isaacson discussing the life an
d impact of Ada Lovelace.(more)

See all videos for this article

Augusta Ada King, the countess of Lovelace, was the daughter of the poet Lord Byron and th
e mathematically inclined Anne Millbanke. One of her tutors was Augustus De Morgan, a fa
mous mathematician and logician. Because Byron was involved in a notorious scandal at the
time of her birth, Lovelace’s mother encouraged her mathematical and scientific interests, h
oping to suppress any inclination to wildness she may have inherited from her father.

Toward that end, Lovelace attended Babbage’s soirees and became fascinated with his Differ
ence Engine. She also corresponded with him, asking pointed questions. It was his plan for t
he Analytical Engine that truly fired her imagination, however. In 1843, at age 27, she had co
me to understand it well enough to publish the definitive paper explaining the device and dr
awing the crucial distinction between this new thing and existing calculators. The Analytical
Engine, she argued, went beyond the bounds of arithmetic. Because it operated on general s
ymbols rather than on numbers, it established “a link…between the operations of matter an
d the abstract mental processes of the most abstract branch of mathematical science.” It wa
s a physical device that was capable of operating in the realm of abstract thought.
Lovelace rightly reported that this was not only something no one had built, it was somethin
g that no one before had even conceived. She went on to become the world’s only expert on
the process of sequencing instructions on the punched cards that the Analytical Engine used;
that is, she became the world’s first computer programmer.

One feature of the Analytical Engine was its ability to place numbers and instructions tempor
arily in its store and return them to its mill for processing at an appropriate time. This was ac
complished by the proper sequencing of instructions and data in its reader, and the ability to
reorder instructions and data gave the machine a flexibility and power that was hard to gras
p. The first electronic digital computers of a century later lacked this ability. It was remarkabl
e that a young scholar realized its importance in 1840, and it would be 100 years before any
one would understand it so well again. In the intervening century, attention would be diverte
d to the calculator and other business machines.