Made by : Mohammed Azeem

boilermakerwrapperElectronics - Devices

Nov 8, 2013 (3 years and 7 months ago)

205 views

Made by

:
Mohammed Azeem




COMPUTER
:




A

computer

is an electronic machine or system that inputs data,
processes it, outputs the result and stores
information. Its components work in unison, and the
absence of any one of them limits the computer from performing user
-
defined functions.


History
of

computer
s

The

abacus

was an early aid for mathematical computations. A skilled abacus operator can work on addition and
subtraction problems at the speed of a person equipped with a hand calculator. In fact, the oldest surviving abacus
was used in 300 B.C. by the Babylonians.

The abacus is still in use today, principally in the far east.

A very old abacus

In 1617 an eccentric (some say mad) Scotsman named John Napier invented

logarithms
, which are a technology
that allows multiplication to be performed via addition. But Napi
er also invented an alternative to tables, where the
logarithm values were carved on ivory sticks which are now called

Napier's Bones
.

An original set of Napier's Bones [photo courtesy IBM]

A more modern set of Napier's Bones

Napier's invention led direc
tly to the

slide rule
, first built in England in 1632 and still in use in the 1960's by the
NASA engineers of the Mercury, Gemini, and Apollo programs which landed men on the moon.

A slide rule

Leonardo da

Vinci (1452
-
1519) made drawings of gear
-
driven calculating machines but apparently never built any.

A Leonardo da Vinci drawing showing gears arranged for computing

The first gear
-
driven calculating machine to actually be built was probably the

calculati
ng clock
, so named by its
inventor, the German professor Wilhelm Schickard in 1623.

Schickard's Calculating Clock

In 1642 Blaise Pascal, at age 19, invented the

Pascaline

. Pascal built 50 of this gear
-
driven one
-
function calculator
(it could only add) b
ut couldn't sell many because of their exorbitant cost and because they really weren't that
accurate (at that time it was not possible to fabricate gears with the required precision). Shown below is an 8 digit
version of the Pascaline, and two views of a 6

digit version:

Pascal's Pascaline [photo © 2002 IEEE]

A 6 digit model for those who couldn't afford the 8 digit model

A Pascaline opened up so you can observe the gears and cylinders which rotated to
display the numerical result

Just a few years after Pascal, the German Gottfried Wilhelm Leibniz (co
-
inventor with Newton of calculus)
managed to build a four
-
function (addition, subtraction, multiplication, and division) calculator that he called the
stepped reckoner

. Although the s
tepped reckoner employed the decimal number system (each drum had 10 flutes),
Leibniz was the first to advocate use of the binary number system which is fundamental to the operation of modern
computers.

Leibniz's Stepped Reckoner (have you ever heard "ca
lculating" referred to as "reckoning"?)

In 1801 the Frenchman Joseph Marie Jacquard invented a power loom called punched cards that could base its
weave (and hence the design on the fabric) upon a pattern automatically read from punched wooden cards, held
together in a long row by rope.

Jacquard's Loom showing the threads and the punched cards

A close
-
up of a Jacquard card

By 1822 the English mathematician

Charles Babbage

was proposing a steam driven calculating machine the size of
a room, which he calle
d the

Difference Engine
. This machine would be able to compute tables of numbers, such as
logarithm tables.

A small section of the type of mechanism employed in Babbage's Difference Engine

Then Babbage invented an engine which he called the

Analytic
Engine
. This device, large as a house and powered
by 6 steam engines. Babbage called the two main parts of his Analytic Engine the "Store" and the "Mill", as both
terms are used in the weaving industry. In a modern computer these same parts are called the

memory unit

and
the

central processing unit

(CPU).

The Analytic Engine also had a key function that distinguishes computers from calculator
s: the conditional
statement.

Herman

Hollerith

proposed and then successfully adopted Jacquard's punched cards for th
e purpose of
computation. Hollerith’s

invention, known as the

Hollerith desk
, consisted of a card reader which sensed the holes
in the cards, a gear driven mechanism which could count, and a large wall of dial indicators to display the results of
the count
.

An operator working at a Hollerith Desk like the one below

Hollerith built a company, the Tabulating Machine Company which, after a few buyouts, eventually became
International Business Machines, known today as

IBM
. IBM grew rapidly and punched cards became ubiquitous.

One early success was the Harvard

Mark I

computer which was built as a partnership between Harvard and IBM in
1944. This was the first programmable digital computer made in the U.S. But it was not a
purely electronic
computer. Instead the Mark I was constructed out of switches, relays, rotating shafts, and clutches. The machine
weighed 5 tons, incorporated 500 miles of wire, was 8 feet tall and 51 feet long, and had a 50 ft rotating shaft
running its
length, turned by a 5 horsepower electric motor. To appreciate the scale of this machine note the four
typewriters in the foreground of the following photo.

The Harvard Mark I: an electro
-
mechanical computer

Here's a close
-
up of one of the Mark I's four p
aper tape readers. A paper tape was an improvement over a box of
punched cards as anyone who has ever dropped
--

and thus shuffled
--

his "stack" knows.

One of the four paper tape readers on the Harvard Mark I (you can observe the punched
paper roll emerg
ing from the bottom)

One of the primary programmers for the Mark I was a woman,

Grace Hopper
. Hopper found the first computer
"bug": a dead moth that had gotten into the Mark I and whose wings were blocking the reading of the holes in the
paper tape.

The first computer bug

In 1953 Grace Hopper invented the first high
-
level language, "Flow
-
matic". A high
-
level language is worthless
without a program
--

known as a

compiler

--

to translate it into the binary language of the computer and hence Grace
Hoppe
r also constructed the world's first compiler.


The

microelectronics revolution

is what allowed the amount of hand
-
crafted wiring seen in the prior photo to b
e
mass
-
produced as an

integrated circuit

which is a small sliver of silicon the size of your thumbnail .

An integrated circuit ("silicon chip")

By the early 1980s this many transistors could be simultaneously fabricated on an integrated circuit.
Today's

Pentium 4

microprocessor contains 42,000,000 transistors in this same thumbnail sized piece of silicon.

It's humorous to remember that in between the Stretch machine (which would be called a

mainframe

today) and the
Apple I (a

desktop computer
) there was a
n entire industry segment referred to as

mini
-
computers
such as the
following PDP
-
12 computer of 1969:

The DEC PDP
-
12

One of the earliest attempts to build an all
-
electronic (that is, no gears, cams, belts, shafts, etc.) digital computer
occurred in 1937 b
y

J. V. Atanasoff
. This machine was the first to store data as a charge on a capacitor, which is
how
today computers store information is

in their main memory (
DRAM

or

dynamic RAM
.

The Atanasoff
-
Be
rry Computer

Another candidate for granddaddy of the mode
rn computer was

Colossus
, built during World War II by Britain for
the purpose of breaking the cryptographic codes used by Germany.

Two views of the code
-
breaking Colossus of Great Britain

The title of forefather of today's all
-
electronic digital
computers is usually awarded to

ENIAC
, which stood for
Electronic Numerical Integrator and Calculator. ENIAC filled a 20 by 40 foot room, weighed 30 tons, and used
more than 18,000 vacuum tubes Only the left half of ENIAC is visible in the first picture, t
he right half was basically
a mirror image of what's visible.


Two views of ENIAC: the "Electronic Numeri
cal Integrator and Calculator"



To reprogram the ENIAC you had to rearrange the patch cords that you can observe on the left in the prior photo,
and

the settings of 3000 switches that you can observe on the right. To program a modern computer, you type out a
program with statements like:

Circumference = 3.14 * diameter

To perform this computation on ENIAC you had to rearrange a large number of patch c
ords and then locate three
particular knobs on that vast wall of knobs and set them to 3, 1, and 4.

Reprogramming ENIAC involved a hike

Even with 18,000 vacuum tubes, ENIAC could only hold 20 numbers at a time. ENIAC's basic clock speed was
100,000 cycles per second. Today's home computers employ clock speeds of 1,000,000,000 cycles per second. Once
ENIAC was finished and proved worthy of
the cost of its development, it took days to change ENIAC's program.
Eckert and
Cauchy are

next teamed up with the mathematician

John von Neumann

to design

EDVAC
, which
pioneered the

stored program
.

In the 1950's, UNIVAC (a contraction of "Universal Automatic Computer") was the household word for "computer"
just as "Kleenex" is for "tissue". The first UNIVAC was sold, appropriately enough, to the Census bureau. UNIVAC
was also the first computer to em
ploy magnetic tape.

A reel
-
to
-
reel tape drive [photo courtesy of The Computer Museum]

By 1955 IBM was selling more computers than UNIVAC and by the 1960's the group of eight companies
selling computers was known as "IBM and the seven dwarfs". In IBM's ca
se it was their own decision to
hire an unknown but aggressive firm called

Microsoft

to provide the software for their

personal
computer

(PC). This lucrative contract allowed Microsoft to grow so dominant that by the year 2000 their
market capitalization.

If you learned computer programming in the 1970's, you dealt with what today are called

mainframe computers
,
such as the IBM 7090 (shown below), IBM
360
, or IBM 370.

The IBM 7094, a typical mainframe
computer


There were 2 ways to interact with a mainfram
e. The first was called

time sharing

because the computer gave each
user a tiny sliver of time in a round
-
robin fashion. Perhaps 100 users would be simultaneously logged on, each
typing on a

teletype

such as the following:

The Teletype was the standard
mechanism used to interact with a time
-
sharing computer

A teletype was a motorized typewriter that could transmit your keystrokes to the mainframe and then print the
computer's response on its roll of paper.

The alternative to time sharing was

batch mode
processing
, where the computer gives its full attention to your
program. In exchange for getting the computer's full attention at run
-
time, you had to agree to prepare your program
off
-
line on a

key punch machine

which generated punch cards.

An IBM Key Pu
nch machine which operates like a typewriter except it produces
punched cards rather than a printed sheet of paper

But things changed fast. By the 1990's a university student would typically own his own computer and have
exclusive use of it in his dorm roo
m.

The original IBM Personal Computer (PC)

This transformation was a result of the invention of the

microprocessor
. A microprocessor (uP) is a computer that is
fabricated on an integrated circuit (IC). Computers had been around for 20 years before the fir
st microprocessor was
developed

at


Intel

in 1971. The micro in the name microprocessor

refers to the physical size. Intel didn't invent the
electronic computer. But they were the first to succeed in cramming an entire computer on a single

chip

(IC).
A
typical Busicom desk calculator

The general purpose computer is adapted to each new purpose by writing a

program

which is a sequence of
instructions stored in memory

The first microprocessor (uP) was Intel 4004. The 4004 consisted of 2300 transistors and w
as clocked at 108 kHz
(i.e., 108,000 times per second). Compare this to the 42 million transistors and the 2 GHz clock rate (i.e.,
2,000,000,000 times per second) used in a Pentium 4. The 8080 was employed in the

MITS Altair

computer, which
was the world's

first

personal computer

(PC).

The Altair 8800, the first PC


FAMILY

OF

COMPUTERS
:


(1)

APPLE MACINTOSH.

(2)

IBM(INTERNATIONAL BUSINESS MACHINES).


APPLE

MACINTOSH

The

original
Macintosh
, the first commercially successful personal computer to use
a

graphical user interface
, rather than a

command line
.

The

Macintosh

or

Mac
, is a series of several lines of

personal computers

designed, developed, and
marketed by

Apple Inc.

The

first Macintosh

was introduced on January 24, 1984; it was the first
commercially successful personal computer to feature a

mouse

and a

graphical user interface

rather than
a

command
-
line interface
.


Current Mac systems are mainly targeted at the home, education, and creative professional markets.
They are the descendants of the original

iMac

and the entry
-
level

Mac mini

desktop models
, the

Mac
Pro

tower

graphics

workstation
, the

Mac Book
,

Mac Book

and

Mac Book

laptops
. The

Xserve

server

was
discontinued January 31, 2011.

iMAC:

An

iMac

computer from August 2009, a modern all
-
in
-
one
Macintosh.

The

iMac

is a range of
all
-
in
-
one

Macintosh

desktop computers

designed and built by

Apple Inc.

In its original form, the

iMac
G3

had a gum
-
drop or egg
-
shaped look, with a

CRT

monitor, mainly enclosed by a colored, translucent
plastic case, which was refreshed early on with a sleek
er design notable for its

slot
-
loaded optical drive
.
The second major revision, the

iMac G4
, moved
the design to a hemispherical base containing all the
main components and an

LCD

monitor on a freely moving arm attached to it. The third/fourth major
revision,

the

iMac G5

and the

Intel iMac

placed all the components immediately behind the display,
creating a slim unified d
esign that tilts only up and down on a simple metal base.

MACINTOSH II
:

The Mac II featured a

Motorola 68020

processor operating at 16

MHz

teamed with
a

Motorola 68881

floating point unit
. The machine shipped with a socket for an MMU, but th
e "Apple
HMMU Chip" (VLSI VI475 chip) was installed that did not implement virtual memory (what it did was that it
translated 24
-
bit addresses to 32
-
bit addresses for the Mac OS which was not 32
-
bit clean until

System
7
). Standard memory was 1

megabyte
, expandable to 68 MB, though not without the special FDHD
upgrade kit; otherwise, 20 MB was the maximum.RAM could be maxed out to 128 MB, however, if t
he
ROMs were upgraded to those used in the IIx (or if

MODE32

was used), as the Mac II's

memory
controller

supported higher
-
density memory mod
ules than did the stock ROM.


MACINTOSH SE
:

The

Macintosh SE

was a

personal computer

manufactured by

Apple

between March

1987
[1]

and
October 1990. This computer marked a significant improvement on the

Macintosh Plus

design and was introduced by
Apple at the same time as the

Macintosh II
. It had a similar case to the

original Macinto
sh

computer, but with slight
differences in color and styling.

MACINTOSH PORTABLE
:

The

Macintosh Portable

was

Apple Inc.
's first attempt at making a

battery
-
powered

portable

Macintosh

personal computer

that held the power of a desktop
Macintosh.

It

was received with
excitement from most critics but with very poor sales to
consumers. It

featured a black and white active
-
matrix LCD
screen in a hinged cover that covered the keyboard when the machine was not in use.

MACINTOSH CLASSIC
:

The

Macintosh Classic

was a

personal
computer

manufactured by

Computer. Production

of
the Classic was prompted by the success of the

Macintosh Plus

and the

S
E
. The system specifications of the Classic
were very similar to its predecessors, with the same 9
-
inch

(23

cm)
monochrome

CRT

display,
512×342

pixel

resolution, and 4

megabyte

(MB)

memory

limit of the older Macintosh computers.

Mac Book Pro
:

T
he

Mac Book

Pro

is a line of

Macintosh

portable

computers

introduced in January 2006 by

Apple
Inc.

It replaced the

PowerBo
ok G4

and was the second model to be announced in the

Apple

Intel transition

(after
the

iMac
). Positioned at the high end of the

Mac Book

family
, the
Mac Book

Pro is currently produced in three sizes:
the 13
-
, 15
-
, and 17
-

inch.

IBM

International Business Machines

(
IBM
)
:


is an

American

multinational

technology

and

consulting

firm headquartered in

Armonk, New York
. IBM
manufactures and sells computer

hardware

and

software
, and it
offers

infrastructure
,

hosting

and

consulting services

in area
s ranging from

mainframe
computers

to

nanotechnology
.


The company was founded in 1911 as the

Computing Tabulating Recording Corporation
, following a
merger of the Computer Scale Company of America and the International Time Recording Company with
the Tabulating Machine Compa
ny.


IBM Personal Computer
s
:

The

IBM Personal Computer
, commonly known as
the

IBM PC
, is the original version and progenitor of the

IBM PC
compatible

hardware

platform
. It is

IBM

model number

5150
, and was
introduced on August 12, 1981.

Alongside "
microcomputer
" and "
home computer
", the term "
personal
computer
" was already in use before 1981. Howeve
r, because of the
success of the IBM Personal Computer, the term

PC

came to mean more
specifically a

microcomputer

compatible with IBM's PC products.

(1)

PC
:

The

CGA

(Color Graphics Adapter) video card could use
a standard

television

set or an

RGB

monitor for display; IBM's RGB
monitor was their display model 5153. The other option that was offered by
IBM was an

MDA

(Monochrome Display Adapter) and their

monochrome
display model 5151
.

XT
:

The "IBM Personal Computer XT", IBM's model 5160, was
an enhanced
machine that was designed for diskette and hard drive
storage introduced two years after the introduction of the "IBM Personal
Computer". It had eight expansion slots and a 10

MB hard disk (
later
versions 20

MB).
It was usually sold with a

Monochrome Display
Adapter

(MDA) video card. The processor was a 4.77

MHz

Intel 8088

and
the expansion

bus

8
-
bit

Industry Standard Architecture

(ISA) with

XT bus
architecture
.

XT/370
:

The IBM Personal Computer XT/370, was an XT with three
custom 8
-
bit cards: the processor card (370PC
-
P), contained a
modified

Motorola
68000

chip,
micro coded

to execute System 370




instructions, a second 68000 to handle bus arbitration and memory
transfers, and a modified

8087

to emulate the S/370

floating
point

instructions. The second card (370PC
-
M) connected to the first
contained 512 kB of memory. The third card (PC3277
-
EM)
,
was a 3270
terminal emulator necessary to install the system soft
ware for the VM/PC
software to run the processors. The computer booted into DOS, then ran
the VM/PC Control Program.



PCjr
:

The IBM PCjr was IBM's first attempt to enter the market for
relatively inexpensive educational and home
-
use personal computers.
The
PCjr, IBM model number 4860, retained the IBM PC's 8088 CPU and BIOS
interface for compatibility, but its cost and differences in the PCjr's
architecture, as well as other design and implementation decisions,
eventually led the PCjr to be a commercial
failure.

Portable
:

The IBM Portable Personal Computer 5155 model 68 was
an early portable computer developed by IBM after the success of
Compaq's suitcase
-
size portable machine (the Compaq Portable). It was
released in February, 1984, and was eventually r
eplaced by the IBM
Convertible. The

Portable was an XT motherboard, transplanted into a
Compaq
-
style luggable case. The system featured 256 kilobytes of
memory (expandable to 512 kB), an added CGA card connected to an
internal monochrome (amber) composite
monitor, and one or two half
-
height 5.25" 360K floppy disk drives.

AT
:

The "IBM Personal Computer/AT" (model 5170),
announced August 1984, used an

Intel 80286

processor, originally running
at
6

MHz. It had a 16
-
bit

ISA bus and 20

MB

hard drive
. A faster model,
running at 8

MHz, housing a 30
-
megabyte hard disk

was introduced i
n
1986.


IBM made some attempt at marketing it as a multi
-
user machine, but it sold
mainly as a faster PC for power users. Early PC/ATs were plagued with
reliability problems, in part because of some software and hardware
incompatibilities, but mostly rela
ted to the internal 20

MB hard disk, and
High Density Floppy Disk Drive
.

While some people blamed IBM's

hard disk controller

card and others
blamed the hard disk
manufacturer

Computer Memories Inc.

(CMI), the
IBM controller card worked fine with other drives, including CMI's 33
-
MB
model.

AT/370
:

The "IBM Personal Computer AT/370 was an AT with two

custom 16
-
bit
cards, running almost the exact same setup as the XT/370.

Convertible
:

The IBM PC Convertible, released April 3, 1986, was IBM's
first laptop computer and was also the first IBM computer to utilize the 3.5"
floppy disk which went on to become the
standard. It

utilized an Intel 80c88
CPU (a CMOS version of the Intel 8088) runn
ing at 4.77

MHz, 256 kB of
RAM (expandable to 640 kB), dual 720 kB 3.5" floppy drives, and a
monochrome CGA
-
compatible LCD screen at a price of $2,000. It weighed
13 pounds (5,8

kg) and featured a built
-
in carrying handle.

Technology
:

Electronics
:

The main

circuit board in an IBM PC is called the

motherboard

(IBM
terminology calls it a

planar
). This mainly carries the

CPU

and

RAM
,
and it has a

bus

with slots for expansion cards.

On the motherboard
are also the ROM subsystem, DMA and IRQ controllers, coprocessor
socket, sound (PC speaker, tone generation) circuitry, and keyboard
interface.

Keyboard
:

The original keyboard for the IBM 5150

The original 1981 IBM PC's keyboard at the

time was an extremely
reliable and high quality electronic keyboard originally developed in
North Carolina for the

Data master

system.



GENERATIONS OF COMPUTERS

The
Five Generations of Computers
:

Webopedia Weekly

Each generation of computer is characterized by a major technological development that fundamentally
changed the way computers operate, resulting in increasingly smaller, cheaper,
and more

powerful and
more efficient and reliable devices.



The history of

computer

development is often referred to in reference to the different generations of
computing

devices
. Each generation of computer is characterized by a major technological development
that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more
p
owerful and more efficient and reliable devices. Read about each generation and the developments that
led to the current devices that we use today.



First Generation (1940
-
1956) Vacuum Tubes:

The first computers used vacuum tubes for circuitry and
magnetic drums

for

memory
, and were
often enormous, taking up entire rooms. They were very expensive to operate and in addition to
using a great deal of
electricity, generated a lot of heat, which was often the cause of malfunctions.

First generation computers relied on

machine language
, the lowest
-
level programming

language understood by
computers, to perform operations, and they could only solve one problem at a time. Input was based on punched
cards and paper tape, and output was displayed on printouts.

The UNIVAC and

ENIAC

computers are examples of first
-
generation computing devices. The UNIVAC was the
first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.


Second Generation (1956
-
1963) Transistors:

Transistors

replaced vacuum tubes and ushered in the second generation of computers.
The transistor was invented in 1947 but did not see widespread use in compu
ters until the late 1950s.
The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster,
cheaper, more energy
-
efficient and more reliable than their first
-
generation predecessors. Though the
transistor still generated a
great deal of heat that subjected the computer to damage, it was a vast
improvement over the vacuum tube. Second
-
generation computers still relied on punched cards for input
and printouts for output.

Second
-
generation computers moved from cryptic

binary

machine language to symbolic, or

assembly
,
languages, which allowed programmers to specify instructions in words.

High
-
level programming
languages

were also being developed at this time, such as early versions of

COBOL

and

FORTRAN
.
These were also the first computers that stored their instructions in their memory, which moved from
a
magnetic drum to magnetic core technology.

The first computers of this generation were developed for the atomic energy industry.


Third Generation (1964
-
1971) Integrated Circuits:

The development of the

integrated circuit

was the hallmark of the third generation of
computers. Transistors were miniaturized and placed on

sili
con

chips
, called

semiconductors
, which
drastically increased the speed and efficiency of computers.

Instead of punched cards and printouts
, users interacted with third generation computers
through

keyboards

and

monitors
and

inter
faced

with an

operating system
, which allowed the device to run
many different

applications

at one time with a central program that m
onitored the memory. Computers for
the first time became accessible to a mass audience because they were smaller and cheaper than their
predecessors.


Fourth Generation (1971
-
Present) Microprocessors:

The

microprocessor

brought the fourth generation of computers, as thousands of
integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room
could now f
it in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components
of the computer

from the

central processing unit

and memory to input/output controls

on a single chip.

In 1981

IBM

introduced its first computer for the home user, and in 1984

Apple

introduced the Macintosh.
Microprocessors also moved out of the rea
lm of desktop computers and into many areas of life as more
and more everyday products began to use microprocessors.

As these small computers became more powerful, they could be linked together to form networks, which
eventually led to the development of t
he Internet. Fourth generation computers also saw the development
of

GUIs
, the

mouse

and

handheld
devices.


Fifth Generation (Present and Beyond) Artificial Intelligence:

Fifth generation computing devices, based on

artificial intelligence
, are still in
development,
though there are some applications, such as

voice recognition
, that are being used today.
The use of

parallel processing

and

superconductors is helping to make artificial intelligence a
reality.

Quantum computation

and molecular and

nanotechnology

will
radically change the face of
computers in years to come. The goal of fifth
-
generation computing is to develop devices that respond
to

natural language

input and are capable of learning and sel
f
-
organization.


TYP
ES OF COMPUTER


Microcomputer

A

microcomputer

is a

computer

with a

microprocessor

as its

central processing unit
. They are physically small compared
to

mainframe and

minicomputers
. Many microcomputers (
when equipped with a keyboard and screen for input and output) are
also

personal computers

(in the generic sense).

Origins
:

The term "Microcomputer" came into popular use

after the introduction of the

minicomputer
, although

Isaac Asimov

used the term
microcomputer in his short story "The Dying Night" as early

as 1956
.T
he microcomputer replaced the many separate components
that made up the minicomputer's CPU with one integrated microprocessor

chip
. The earliest models such a
s the

Altair 8800

were
often sold as kits to be assembled by the user, and came with as little as 256

bytes

of

RAM
, and
no

input

devices other than
indicator lights and switches, useful as a

proof of concept

to demo
nstrate what such a simple device could do. However, as
microprocessors and

semiconductor memory

became less expensive, microcomputers in turn grew cheaper and easier to use:



Increasingly in
expensive logic chips such as the

7400 series

allowed cheap dedicated circuitry for improved

user
interfaces

such as

keyboard

input, instead of simply a row of switches to toggle bits one at a time.



Use of

audio cassettes

for inexpensive data storage replaced manual re
-
entry of a program every time the device was powered
on.



Large cheap arrays of silicon

logic gates

in the form of

Read
-
only memory

and

EPROMs

allowed utility programs and self
-
booting

kernels

to be stored within
microcomputers. And

only one of the
thing

that happened These

stored programs

could
automatically load further more complex software from external storage devices without user intervention, to form an
inexpensive

turnkey system

that does
not require a computer expert to understand or to use the device.



Random access memory

became cheap enough to afford dedicating approximately 1
-
2 kilobytes of memor
y to a

video display
controller

frame buffer
, for a 40x25 or 80x25 text display
or blocky color graphics on a common household

television
. This
replaced the slow, complex, and expensive

teletypewriter

that was previously common as an interface to minicomputers and
mainframes.

A microcomputer comes equipped with at least one type of data storage, usually

RAM
. Alt
hough some microcomputers (particularly
early 8
-
bit home micros) perform tasks using RAM alone, some form of

secondary storage

is normally desirable.

Minicomputer


A

minicomputer

(colloquially,

mini
) is a class of multi
-
user

computers

that lies in the middle range
of the computing spectrum, in between the largest

multi
-
user systems

(
mainframe computers
) and the smallest single
-
user
systems (
microcomputers

or

personal computers
). The class at one time formed a distinct group with its

own hardware and
operating systems, but the contemporary term for this class of system is

midrange computer
, such as the higher
-
end

SPARC
,

POWER

and

Itanium

-
based systems from

Sun Microsystems
,

IBM

and

Hewlett
-
Packard
.



The minicomputer's industrial impact and heritage
:

Several pioneering computer companies first built minicomputers, such as

DEC
,

Data General
, and

Hewlett
-
Packard
(HP)

(who now refers to its

HP3000

minicomputers as “servers” rather than “minicomputers”). And
although today’s PCs and
servers are clearly microcomputers physically, architecturally their CPUs and operating systems have evolved largely by
integrating features from minicomputers.

In the software context, the relatively simple OSs for early microcomp
uters were usually inspired by minicomputer OSs (such
as

CP/M
's similarity to Digital's

RSTS
) and multiuser OSs of today are often either insp
ired by or directly descended from
minicomputer OSs (
UNIX

was originally a minicomputer OS, while

Windows NT

the foundation for all current
versions
of

Microsoft Windows

borrowed design ideas liberally from

VMS

and UNIX). Many of the first generation of PC
programmer
s were educated on minicomputer systems.

Mainframe computer


An

IBM 704

mainframe

Mainframes

are powerful

computers

used mainly by
large organizations for critical applications, typically bulk data processing such
as

census
, industry and consumer statistics,

enterprise resource planning
, and financial

transaction processing
.

Characteristics
:

Nearly all mainframes have the ability to run (or host) multiple
operating systems, and thereby operate not as a single computer but
as a number of

virtual machines
. In this role, a single mainframe can replace dozens or even hundreds of s
maller

servers
. While
mainframes pioneered this capability, virtualization is now available on most families of computer systems, though not always

to the
same degree o
r level of sophistication.

Mainframes can add or

hot swap

system capacity
none

disruptively and granularly, to a level of sophistication usually not found on
most servers. Modern mainframes, notably the IBM

zSeries
,
System z9

and

System z10

servers, offer two levels of

virtualization
:

logical partitions (
LPARs
, via the

PR/SM

facility) and virtual machines (via the

z/VM

operating system). Some IBM mainframe
customers run no more than two
machines

: one in their primary data center, and one in their

backup data center

fully active,
parti
ally active, or on standby

in case there is a catastrophe affecting the first building. Test, development, training, and production
workload for applications and databases can run on a single machine, except for extremely large demands where the capacity o
f
one machine might be limiting. Such a two
-
mainframe installation can support continuous business service, avoiding both planned
and unplanned outages. In practice most customers use multiple mainframes linked by

Parallel
Simplex

and shared

DASD
.

Mainframes are designed to handle very high volume input and output (I/O
) and emphasize throughput computing
.

Mainframes also have execution integrity characteristics for

fault tolerant

computing.

Differences from supercomputers
:

A

supercomputer

is a computer that is at the frontline of current processing capacity, particularly speed of calculation.
Supercomputers are used for scientific and engineering problems (
high
-
performance computing
) which are limited by processing
speed and memory size, while mainframes are used for problems which are limited by data movement in input/output devices,
reliability, and

for handling multiple business transactions concurrently. The differences are as follows:



Mainframes are measured in millions of instructions per second (
MIP
S
) while assuming typical instructions are integer
operations, but supercomputers are measured in

floating point

operations per second (
FLOPS
). E
xamples of integer
operations include moving data around in memory or checking values. Floating point operations are mostly addition,
subtraction, and multiplication with enough digits of precision to model continuous phenomena such as weather prediction a
nd
nuclear simulations. In terms of computational ability, supercomputers are more powerful.
[10]



Mainframes are built to be reliable for transaction processing as it is
commonly understood in the business world: a commercial
exchange of goods, services, or money. A typical transaction, as defined by the

Transaction Processing Performan
ce
Council
,would include the updating to a database system for such things as inventory control (goods), airline reservations
(services), or banking (money). A transaction could refer to a set of operations including disk read/writes, operating system

call
s, or some form of data transfer from one subsystem to another. This operation does not count toward the processing
power of a computer. Transaction processing is not exclusive to mainframes but also used in the performance of
microprocessor
-
based servers
and online networks.

Supercomputers

The

Columbia Supercomputer
, located at the

NASA Ames Research Center
.

A 1985 supercomputer

Cray
-
2

A

supercomputer

is a

computer

that is at the frontline of current processing capacity, particularly speed of calculation.
Supercomputers were introduced in the 1960s and were designed primarily by

Seymour Cray

at

Control Data Corporation

(CDC),
which led the market into the 1970s until Cray left to form his own company,

Cray Research
.

Today, supercomputers are typically one
-
of
-
a
-
kind custom designs produced by "traditional" companies such
as

Cray
,

IBM

and

Hewlett
-
Packard
. Since October 2010, the

Tianhe
-
1A

supercomputer has been the fastest in the world; it is
located in

China
.

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

quantum physics
,

weather forecasting
,
climate research,
molecular modeling

(computing the structures and properties of chemi
cal compounds, biological

macromolecules
,
polymers, and crystals), physical simulations (such as simulation of airplanes in

wind tunnels
, simulation of the detonation of

nuclear
weapons
, and research into

nuclear
fusion
).

Special
-
purpose supercomputers
:

Special
-
purpose supercomputers

are high
-
performance computing devices with a hardware architecture
dedicated to a single problem. This allows the use of specially programmed

FPGA

chips or even
custom

VLSI

chips, al
lowing higher price/performance ratios by sacrificing generality. They are used for
applications such as

astrophysics

computation and brute
-
force

codebreaking
. Historically a new special
-
purpose supercomputer has occasionally been faster than the world's fastest general
-
purpose
supercomputer, by some measure. For example, GRAPE
-
6 was faster than the Earth Simulator in 2002 for
a
particular special set of problems.

Current fastest supercomputer system
:

Tianhe
-
1A

is ranked on the TOP500 list as the fastest supercomputer. It consists of 14,336

Intel

Xeon CPUs and 7,168

Nvidia

Tesla
M2050 GPUs with a new interconnect fabric of Chinese origin, reportedly twice the speed of

InfiniBand
.Tianhe
-
1A spans 103
cabinets, weighs 155 tons, and consumes 4.04 megawatts of electricity.


In popular
culture
:

In

the movie,

2001: A
Space Odyssey
, the

HAL 9000

supercomputer is shown to have achieved

sentience
.

MODES OF COMPUTERS




Since the
invention of computers from first generation and fourth
generation computers, they have been classified according to their types and how they operate that is
input, process and output information. Below you will get a brief discussion on various types of
C
omputers we have

Computer types can be divided into 3 categories according to electronic nature. Types of computers are
classified according to how a particular Computer functions. These computer types are
;

1.

Analogue Computers

2.

Digital Computers

3.

Hybrid Computers

1.
Analogue Computers
:




Analogue types of Computer uses what is known as analogue signals that are
represented by a continuous set of varying voltages and are used in scientific research centers?,
hospitals and flight centers

With
analogue types of computer no values are represented by physical measurable quantities e.g.
voltages. Analogue computer types program arithmetic and logical operations by measuring physical
changes i.e. temperatures or pressure.

2.
Digital Computer type
:


With these types of computers operation are on electrical input that can attain two inputs,
states of ON=1 and state of OFF = 0. With digital type of computers data is represented by digital of 0
and 1 or off state and on state. Digital computer type reco
gnizes data by counting discrete signal of (0 0r
1), they are high speed programmable; they compute values and stores results. After looking at the
Digital computer type and how it functions will move to the third computer type as mentioned above.

3.
Hybrid

type of Computer
:





Hybrid computer types are very unique, in the sense that they combined both analogue
and digital features and operations. With Hybrid computers operate by using digital to analogue convertor
and analogue to digital convertor. By
linking the two types of computer above you come up with this new
computer type called Hybrid.

I hope this article on computer types gives you a basic foundation of how computers are classified and
how they operate. Next article will focuses on computer si
zes definition and characteristics
.

NAMES:

LOTFI ASKAR ZADEH

Lotfali Askar Zadeh

(born February 4, 1921), better known as

Lotfi A. Zadeh
, is a mathematician, electrical engineer,
computer scientist, and a professor of

computer science

at the

University of California, Berkeley
. Zadeh describes
himself in an interview with Jeanne
Spriter James as an

American
, mathematically oriented, electrical engineer
of

Iranian

descent, bor
n in Russia.


Zadeh was born in

Baku
,

Azerbaijan SSR
,to an

Iranian Azeri

father from

Ardabil
, Rahim
Aleskerzade, who was a journalist on assignment from Iran, and a

Russian

Jewish

mother, Fanya
Koriman, who was a

pediatrician
.

Work
:

Because of the importance of the relaxation of Aristotelia
n logic, which opens up applicability of rational
methods to the majority of practical situations without dichotomous

truth values
, Zadeh is one of the most
referenced authors in the

fields of

applied mathematics

and

computer science
, but


as noted below


his
contributions are not limited to fuzzy sets and s
ystems.

Fuzzy sets and systems
:

Aristotle

introduced

the

laws of thought
, which consisted of three fundamental laws:



Principle of identity



Law of the excluded middle



Law of contradiction
.

The

law of the excluded middle

states that for all propositions

p
, either

p

or

~p

must be true, there being
no middle true proposition between them. This should not be confused with the

principle of bivalence
,
which states that either

p

must be true or false.

Jan Łukasiewicz

was the first to propose a systema
tic alternative to the bi
-
valued logic of Aristotle and
described the 3
-
valued logic, with the third value being

Possible
. Zadeh, in his theory of

fuzzy sets
,
proposed using a

membership function

(with a

range

covering the

interval

[0,1]) operating on
the

domain

of all possible values. He proposed new operations for the ca
lculus of logic and showed
that

fuzzy logic

was a generalisation of classical and Boolean

logic
. He also proposed

fuzzy numbers

as a
special case of fuzzy sets, as well as the corresponding rules for consistent mathematical operations
(fuzzy arithmetic).

Other contributions
:

Lotfi Zadeh is also credited, along with

John R. Ragazzini
, in 1952, with having pioneered the
development of the

z
-
transform

method in discrete time signal processing and analysi
s. These methods
are now standard in

digital signal processing
,

digital control
, and other discrete
-
time systems used in
ind
ustry and research. He is an editor of

International Journal of Computational Cognition
.

Zadeh's latest work includes

computing with words and perceptions
. His recent papers include

From
Search Engines to

Question
-
Answering Systems

The Role of Fuzzy Logic
, Progress in Informatics, No.
1, 1
-
3, 2005; and

Toward a Generalized Theory of Uncertainty (GTU)

An Outline
, Information Sciences,
Elsevier, Vol. 172, 1
-
40, 2005.

BLAISE PASCAL


Blaise Pascal

(1623
-
1662)



Blaise Pascal is credited with inventing an early calculator.




Blaise Pascal, the French scientist was one of the most reputed
mathematician and physicist of
his time. He is credited with
inventing an early calculator, amazingly advanced for its time. A
genuis from a young age, Blaise Pascal composed a treatise on
the communication of sounds at the age of twelve, and at the age
of sixteen he composed a treatise

on conic sections.

The Pascaline
:

The idea of using machines to solve mathematical problems can be traced at least as far as
the early 17th century. Mathematicians who designed and implemented calculators that were
capable of addition, subtraction, multiplication, and division included Wil
helm Schickhard,
Blaise Pascal, and Gottfried Leibnitz. In 1642, at the age of eighteen
Bl
aise

Pascal invented
his numerical wheel calculator called the Pascaline to help his father a French tax collector
count taxes. The Pascaline had eight movable dials
that added up to eight figured long sums
and used base ten. When the first dial (one's column) moved ten notches
-

the second dial
moved one notch to represent the ten's column reading of 10
-

and when the ten dial moved
ten notches the third dial (hundred
's column) moved one notch to represent one hundred
and so on.

Roulette Machine
:

Blaise Pascal introduced a very primitive version of the roulette machine in the 17th century.
The

roulette

was a by
-
product of Blaise Pascal's attempts to invent a
perpetual motion machine
.

Wrist Watch
:

The first reported person to
actually wear a

watch on the wrist

was the French mathematician
and philosopher, Blaise Pascal. With a piece of string, he attached his pocket watch to his
wrist.


Pascal (Pa)
:

Unit
of atmospheric pressure named in honor of Blaise Pascal, whose experiments greatly



increased knowledge of the atmosphere. A pascal is the force of one newton acting on a
surface area of one square meter. It is the unit of pressure designated by the Interna
tional
System. l00,OOO Pa= 1000mb 1 bar

Pascal
:

Blaise Pascal's contribution to computing was recognized by computer scientist Nicklaus
Wirth, who in 1972 named his new computer language Pascal (and insisted that it be spelled
Pascal, not PASCAL).

WORDS
OF WISDOM:



The heart has its reasons that the mind knows nothing of. "
-

Blaise Pascal


"If God does not exist, one will lose nothing by believing in him, while if he does exist, one will lose
everything by not believing."


-

Blaise Pascal


"Since we canno
t know all that there is to be known about anything, we ought to know a little about
everything."
-

Blaise Pascal
.

NORBERT WIENER

Norbert Wiener

was

an

American

mathematician. A

famous

child prodigy
, Wiener later
became an early studier of

stochastic

and

noise

processes, contributing work relevant to

electronic
engineering
,
electronic communication
, and

control systems
.

Wiener is regarded as the originator of

cybernetics
, a
formalization of the notion of

feedback
, with many
implications for

engineering
,

control, computer
,

biology
,

philosophy
, and the organization of

society
.

Work:

Information is information, not matter or energy.


Norbert Wiener,

Cybernetics:

Or the Control and Communication in the Animal and the Machine

Wiener was an early studier of

stochastic

and

noise

processes, contributing work relevant to

electronic
engineering
,

electronic commun
ication
, and

control systems
.

Wiener is regarded as the originator of

cybernetics
, a formalization of the notion of

feedback
, with many
implications for

engineering
,

systems control
,

computer science
,

biology
,

philosophy
, and the organization
of

society
.

Wiener's work with

cybernetics

influenced

Gregory Bateson

and

Margaret Mead
, and through
them,

Anthropology
,

Sociology
, and

Education
.
[11]

In the mathematical field of probability, the "
Wiener sausage
" is a neighborhood of
the trace of a

Brownian motion

up to a time

t
, given by taking all points within a fixed distance of Brownian
motion. It can be visualized as a cylinder of fixed radius the centerline of which is Brownian motion.

(1)
Wiener
equation:

A simple mathematical representation of

Brownian motion
, the

Wiener equation
, named after Wiener,
assumes the current

velocity

of a

fluid

particle fluctuates.

(2)
Wiener filter:

For signal processing, the

Wiener
filter

is a

filter

proposed by Wiener during the 1940s and published in
1949. Its purpose is to reduce the amount
of

noise

present in a signal by compar
ison with an estimation of
the desired noiseless signal.

(3)
In mathematics:

Wiener took a great interest in the mathematical theory of

Brownian motion

proving many results now
widely known such
as the non
-
differentiability of the paths. As a result the one
-
dimensional version of
Brownian motion became known as the

Wiener process
. It is the best known of the

Lévy
processes
,

càdlàg

stochastic processes with stationary statistically independent increments, and occurs
frequently in pure and applied mathema
tics, physics and economics
.

Claude Shannon

Claude Elwood Shannon

was an

American

mathematician
,

electronic engineer
,
and

cryptographer

known as "the father of

Information Theory
".

Boolean theory
:


While studying the complicated ad hoc circuits of the differential analyzer, Shannon saw that Boole's
concepts could be used to great utility. A paper drawn from his 1937 master's

thesis
,

A Symbolic Analysis
of Relay and Switching Circuits
,was published in the 1938 issue of the

Transactions of the American
Institute of Electrical Engineers
. It also earned Shannon the

Alfred Noble American Institute of American
Engineers Award

in 1940.

Howard Gardner
, of

Harvard University
, called S
hannon's thesis "possibly the
most important, and also the most famous, master's thesis of the century."

In this work, Shannon proved that

Boolean algebra

and

binary arithmetic

could be used to simplify the
arrangement of the electromechanical

relays

then used in te
lephone routing switches, then expanded the
concept and also proved that it should be possible to use arrangements of relays to solve Boolean
algebra
prob
lems.

In

1940, Shannon became a National Research Fellow at the

Institute for Advanced
Study

in Princeton, New Jersey. At Princeton, Shannon had the opportunity to discuss his ideas with
influential scientists and mathematicians such as

Hermann Weyl

and

John von Neumann
, and even had
the occasional encounter with

Albert E
instein
. Shannon worked freely across disciplines, and began to
shape the ideas that would become information theory.

Other work
:

Shannon and his famous

electromechanical

mouse

Theseus

(named after

Theseus

from
Greek mythology) which he tried to have solve the maze in one of the first experiments in

artificial
intelligence
.

Shannon's mouse
:

These us
, created in 1950, was a magnetic mouse controlled by a relay circuit that enabled it to move
around a maze of 25 squares. Its dimensions were the same as an average mouse.

Shannon's mouse
appears to have been the first learning device of its kind.

Shannon's computer chess program
:

In 1950 Shannon published a groundbreaking paper on

computer chess

entitled

Programming a
Computer for

Playing Chess
. It describes how a machine or computer could be made to play a
reasonable game of

chess
. His process for having the computer decide on which move to make is
a

minimax

procedure, based on an

evaluation function

of a given chess position. Shannon gave a rough
example of an evaluation function in which the valu
e of the black position was subtracted from that of the
white position.

Material

was counted according to the usual relative

chess piece relative value

.

He
considered some positional
factors, subtracting ½ point for each

doubled pawns
,

backward pawn
,
and

isolated pawn
. Another positional factor in the evaluation function was

mobility
, adding 0.1 point for
each legal move available. Finally, he considered

checkmate

to be the capture of the king, and gave the
king the artificial value of 200 points.

Shannon's maxim
:

Shannon formulated a version of

Kerckhoffs' principle

as "the enemy knows the system". In this form
it is known as "Shannon's maxim".

BILL GATES
.


William Henry

"
Bill
"

Gates III
, (born October 28, 1955)

is an American

business
magnate
,

philanthropist
,

author

and is

chairman

of

Microsoft

the software company he founded with

Paul
Allen

Gates is one of the bes
t
-
known entrepreneurs of the personal computer revolution
.

IBM PARTNERSHIP:

In 1980,

IBM

approached Microsoft to write the BASIC interpreter for its upcoming personal
computer, the

IBM PC
. When IBM's representatives mentioned that they needed an operating
system, Gates referred them to

Digital Research

(DRI), ma
kers of the widely
used

CP/M

operating system. Gates proposed using

86
-
DOS

(QDOS), an operating system
similar to CP/M that

Tim Paterson

of

Seattle Computer Products

(SCP) had made for hardware
similar to the PC. Microsoft made a deal with SCP to become the exclusive licensing age
nt, and
later the full owner, of 86
-
DOS. After adapting the operating system for the PC, Microsoft
delivered it to IBM as

PC
-
DOS

in exchange for a one
-
time fee of $50,000. They did, an
d the
sales of

MS
-
DOS

made Microsoft a major player in the industry.

Windows
:

Microsoft launched its first retail version of

Microsoft
Windows

on November 20, 1985, and in
August, the company struck a deal with

IBM

to develop a separate operating system
called

OS/2
. Although the two companie
s successfully developed the first version of the new
system, mounting creative differences undermined the partnership. Gates distributed an internal
memo on May 16, 1991, announcing that the OS/2 partnership was over and Microsoft would
shift its efforts
to the

Windows NT

kernel

development.


Philanthropy
:


Gates began to realize the expectations others had of him when public opinion mounted
that he could give more of his wealth to charity. Gates studied the work of

Andrew
Carnegie

and

John D. Rockefeller

and in 1994 sold some of his Microsoft stock to create the
William H. Gates Foundation. In 2000, Gates and his wife combined three family foundations
into one to create th
e charitable

Bill & Melinda Gates Foundation
, which is the largest
transparently operated charitable foundation in the world.


Bibliography
:

Gates has authored two books
:



The Road Ahead

(1995)



Business @ the Speed of Thought

(1999)
.

HERMAN HOLLERITH

Herman Hollerith


was an

American

statistician

who developed a mechanical

tabulator

based
on

punched cards

to rapidly tabulate statistics from millions of pieces of data. He was the founder of one
of the companies that later merged and bec
ame

IBM
.

Electronic tabulation of data:

Hollerith tabulating machine and sorter

At the urging of

John Shaw Billings
, Hollerith developed a
mechanism using electrical connections to
trigger a counter, recording information. A key idea was that data could be coded numerically.
Hollerith saw that if numbers could be punched in specified locations on a card, in the now familiar
rows and columns,
then the cards could be counted or sorted mechanically and the data recorded. A
description of this system,

An Electric Tabulating System (1889)
, was submitted by Hollerith to
Columbia University as his doctoral thesis, and is reprinted in Randell's book.O
n January 8, 1889,
Hollerith was issued U.S. Patent 395,782
,
claim 2 of which reads:

The herein
-
described method of compiling statistics, which consists in recording separate statistical
items pertaining to the individual by holes or combinations of holes p
unched in sheets of electrically
non
-
conducting material, and bearing a specific relation to each other and to a standard, and then
counting or tallying such statistical items separately or in combination by means of mechanical
counters operated by electro
-
magnets the circuits through which are controlled by the perforated
sheets, substantially as and for the purpose set forth.


Inventions and businesses
:

Hollerith punched card

Hollerith had left teaching and begun working for the

United States Census Office

in the year he filed
his first patent application. Titled "Art of Compiling Statistics", it was filed on September 23, 1884;

U.S. Patent 395,782 was granted on January 8, 1889.


Hollerith built machines under contract for the Census Office, which used them to tabulate the

189
0
census

in only one
year. The

1880 census

had taken eight years. Hollerith then started his own
business in 1896, founding the

Tabulating Machine
Compa
ny
.

To

make his system work, he invented
the first automatic card
-
feed mechanism and the first

key punch

(that is, a punch operated by
a

keyboard
); a skilled operator could punch 200

300 cards per hour. He also invented a

tabulator
.
The

1890 Tabulator

was

hardwired

to operate only on 1890 Census cards. A

control panel

in his 1906
Type I Tabulator allowed it to do different jobs without being rebuilt (the first step towards
programming). These inventions were among the foundations o
f the modern information processing
industry.

In 1911 four corporations, including Hollerith's firm, merged to form the

Computing Tabulating
Recording Corporation

(CTR)
.Under the presidency
of

Thomas
, it was renamed

International
Business Machines Corporation (IBM)

in 1924.

GEORGE BOOLE

George Boole

was

an

English

mathematician

and

philosopher
.

As th
e inventor of

Boolean logic

the basis of modern digital

computer

logic

Boole is regarded in
hindsight as a founder of the field of

computer science
. Boole said,

... no general method for the solution of questions in the theory of probabilities can be established
which does not explicitly
recognize

... those universal laws of
thought which are the basis of all
reasoning ...

Work:


His earliest published paper was the "Researches in the theory of analytical transformations, with a
special application to the reduction of the general equation of the second order." A long li
st of Boole's
memoirs and detached papers, both on logical and mathematical topics, are found in the

Catalogue of
Scientific Memoirs

published by the

Royal Society
, and in the supplementary volume
on

Differential
Equations
, edited by

Isaac Todhunter
. To the

Cambridge Mathematical Journal

and its

successor,
the

Cambridge

and

Dublin

Mathematical Journal
, Boole contributed twenty
-
two articles in all. In the third
and fourth series of the

Philos
ophical Magazine

are found sixteen papers. The Royal Society printed six
important memoirs in the

Philosophical Transactions
, and a few other memoirs are to be found in
the

Transactions of the

Royal Society of Edinburgh

and of the

Royal Irish Academy
, in the

Bulletin de
l'Académie de St
-
Pétersbourg

for 1862, and in

Crelle's Journal
. Also included is a paper on the
mathematical basis of logic, published in the

Mechanic's Magazine

in 1848. The works of Boole are thus
contained in about fifty scattered articles and a few separate publications.

Detail of stained
glass window in Lincoln Cathedral dedicated to George Boole

Only two systematic

treatises

on mathematical subjects were completed by Boole during his lifetime.
The well
-
known

Treatise on D
ifferential
Equations

appeared

in 1859, and was followed, the next year,
by a

Treatise on the

Calculus

of Finite Differences
, designed to serve as a sequel to the former work.
His principal characterist
ic was perfect confidence in any result obtained by the treatment of symbols
in accordance with their primary laws and conditions, and an almost unrivaled skill and power in
tracing out these results.

With the exception of

Augustus De Morgan
, Boole was probably the first English mathematician since
the time of

John Wallis

who had also written
upon

logic
. Boole afterward regarded this as a

hasty and
imperfect exposition of his logical system, and he desired that his much larger work,

An Investigation
of the Laws of Thought (1854), on Which are Founded
the Mathematical Theories of Logic and
Probabilities
, should alone be considered as containing a mature statement of his views.

Plaque beneath Boole's window in Lincoln Cathedral

He did not regard logic as a branch of mathematics, as the title of his earl
ier pamphlet might be taken
to imply, but he pointed out such a deep

analogy between

the symbols of

algebra

and those that can
be made, in his opinion, to represent

logical forms

and

syllogisms
, that we can hardly help saying that
formal logic is mathematics restricted to the two quantities, 0 and 1. By unity Bo
ole denoted the
universe of thinkable objects;

literal symbols
, such as

x
,

y
,

z
,

v
,

u
, etc., were used with the elective
meaning attaching to common adjectives and substantives. Thus, if

x

= horned and

y

= sheep, then
the successive acts of election
represented by

x

and

y
, if performed on unity, give the whole of the
class horned sheep. Boole showed that elective symbols of this kind obey the same primary laws
of

combination

as algebraic symbols
, whence it followed that they could be added, subtracted,
multiplied and even divided, almost exactly in the same manner as numbers. Thus, (1


x
) would
represent the operation of selecting all things in the world except horned things, that is, all not ho
rned
things, and (1


x
) (1


y
) would give us all things neither horned nor sheep. By the use of such
symbols

propositions

could be reduced to the form of

equations
, and the syllogistic conclusion from
two

premises

was obtained by eliminating the middle term according to ord
inary algebraic rules.

CHARLES BABBAGE

Charles Babbage was born in London Dec. 26, 1791, St. Stephan day, in
London.



Difference engine:

Babbage presented something that he called "difference engine" to the
Royal Astronomical Society on Jun 14, 1822 and
in a paper entitled "Note on the
application of machinery to the computation of astronomical and mathematical tables."


It was able to calculate polynomials by using a numerical method called the differences
method.




Charles wrote, "The drawings and pa
rts of the Engine are at length in a place of safety

I am almost worn out with disgust and annoyance at the whole affair." In 1842 the
government officially abandoned the project.



Analytical engine:

Between 1833 and 1842 he tried to build a machine that
would be programmable to do
any kind of calculation, not just ones relating to polynomial equations. The first
breakthrough came when he redirected the machine's output to the input for further
equations. He described this as the machine "eating its own ta
il". It did not take much
longer for him to define the main points of his analytical engine.



The mature analytical engine used punched cards adapted from the Jacquard loom to
specify input and the calculations to perform. The engine consisted of two part
s: the mill
and the store. The mill, analogous to a modern computer's CPU, executed the operations
on values retrieved from the store, which we would consider memory. It was the world's
first general
-
purpose computer.



A design for this emerged by 1835. B
abbage and a handful of assistants created 500
large design drawings, 1000 sheets of mechanical notation, and 7000 sheets of
scribbles. The completed mill would measure 15 feet tall and 6 feet in diameter. The 100
digit store would stretch to 25 feet long.

Babbage constructed only small test parts for
his new engine; a full engine was never completed.



Second Difference Engine:

Between October 1846 and March 1849 Babbage started designing a second difference
engine using knowledge gained from the analytica
l engine. It used only about 8000
parts, three times fewer than the first. It was a marvel of mechanical engineering.



Unlike the analytical engine that he continually tweaked and modified, he did not try to
improve the second difference engine after comp
leting the initial design. Babbage made
no attempt to actually construct the machine.



The 24 schematics remained in the Science Museum archives until a full
-
size replica was
built 1985
-
1991 to celebrate the 200th anniversary of Babbage’s birth. It measur
ed 11
feet long, 7 feet high and 18 inches deep, and weighted 2.6 tonnes. The limits of
precision were restricted to those achievable by Babbage.