Sunday, November 20, 2016

PHOTOCOPIER MACHINE




There are plenty of machines in each office nowadays – laptops, desk computers, lamps, printers, faxes, tablets, photocopiers, smart phones. All of these are suited for our needs and easy to work with, but the technology behind them is sometimes unknown.

Today let us throw some light on one of the most common machines used worldwide i.e. photocopier machine.

Photocopying is a process which makes paper copies of documents and other visual images quickly and cheaply.

It was introduced by Xerox in the 1960s, and over the following 20 years it gradually replaced copies made by carbon paper, mimeograph machines and other duplicating machines.

Chester Carlson, the inventor of photocopying, was originally a patent attorney and part time researcher and inventor. As he worked at his job, he noted that there never seemed to be enough carbon copies of patent specifications, and there seemed to be no quick or practical way of getting more. The choices were limited to sending for expensive photo copies, or having the documents retyped and then reread for errors.

Carlson was frustrated from painful attacks of arthritis. He found this a painful and tedious process. This prompted him to conduct experiments in the area of photoconductivity, through which multiple copies could be made with minimal effort.








Carlson decided to dip into his meagre resources to pursue his research. He set up a small lab in nearby Astoria and hired an unemployed young physicist, a German refugee named Otto Kornei, to help with the lab work.

It was here, in a rented second-floor room above a bar, where xerography was invented.


This is Carlson's account of that moment: "I went to the lab that day and Otto had a freshly-prepared sulfur coating on a zinc plate. We tried to see what we could do toward making a visible image. Otto took a glass microscope slide and printed on it in India ink the notation '10-22-38 ASTORIA.' We pulled down the shade to make the room as dark as possible, then he rubbed the sulfur surface vigorously with a handkerchief to apply an electrostatic charge, laid the slide on the surface and placed the combination under a bright incandescent lamp for a few seconds. The slide was then removed and lycopodium powder was sprinkled on the sulfur surface. By gently blowing on the surface, all the loose powder was removed and there was left on the surface a near-perfect duplicate in powder of the notation which had been printed on the glass slide”. 



This process was repeated several times to convince that it was true, then they made some permanent copies by transferring the powder images to wax paper and heating the sheets to melt the wax.

Carlson tried to sell his invention to some companies, but because the process was still underdeveloped he failed.

From 1939 to 1944, he was turned down by more than twenty companies. Even the National Inventors Council dismissed his work. How difficult it was to convince anyone that tiny plates and rough image held the key to a tremendous new industry. The years went by without a serious nibble. Carlson became discouraged and several times decided to drop the idea completely. But each time he returned to try again.

Finally, in 1944, Battelle Memorial Institute, a non-profit research organization, in Columbus, Ohio, became interested, signed a royalty-sharing contract with Carlson, and began to develop the process.

In 1947 Haloid, a small New York based organisation manufacturing and selling photographic paper at that time, approached Battelle to obtain a license to develop and market a copying machine based on this technology. Battelle entered into an agreement with Haloid (later to be known as Xerox), giving Haloid the right to develop a xerographic machine.

In 1955, Haloid - by then Haloid Xerox - produced Copyflo, the first automated xerographic machine. It produced enlarged prints on a continuous roll from microfilm originals, and spawned a line of Xerox microsystems products which are still turning significant profits. Copyflo was also the first product to use a drum, instead of a plate, as the photoconductive surface. The rotating drum, an ingenious solution to the problem of how to make copies quickly, has been used again and again in Xerox machines.



However, it wasn't until 22 years after electro photography had first been conceived that the first true office copier was produced. In 1958, the introduction of the first-ever commercial push button photocopier machine Model the “Xerox 914” turned into success. It was called ‘914’ because it could handle paper legal size paper which is 9 inches x 14 inches in size. The success of “Xerox 914” was so huge that the company changes its name to Haloid Xerox in 1958.

The name was chosen based on the unique dry printing technique, and shortened to follow the model set by the other big company at the time – Kodak. Three years later, another renaming occurred and the company was called simply Xerox.

This was the model that hit it big that by 1965 earned Xerox revenue over $500 million dollars and today Xerox is such a household name that people confuse the name of the company for the process called photocopying!






Friday, November 18, 2016

CALCULATOR



CALCULATOR

Calculation was a need from the early days when it was necessary to account to others for individual or group actions, particularly in relation to maintaining inventories or reconciling finances. Early man counted by means of matching one set of objects with another set (stones and sheep). The operations of addition and subtraction were simply the operations of adding or subtracting groups of objects to the sack of counting stones or pebbles. 

ROMAN ABACUS


In the very beginning, of course was the abacus, a sort of hand operated mechanical calculator using beads on rods, first used by Sumerians and Egyptians around 2000 BC.
The principle was simple, a frame holding a series of rods, with ten sliding beads on each. When all the beads had been slid across the first rod, it was time to move one across on the next, showing the number of tens, and thence to the next rod, showing hundreds, and so on (with the ten beads on the initial row returned to the original position).
John Napier dramatically advances the understanding of number relationships in 1614 with his invention of logarithms. Since logarithms are the foundation on which the slide rule is built, its history rightly begins with him. His early concept of simplifying mathematical calculations through logarithms makes possible the slide rule as we know it today.
Napier himself contributes Napier’s Bones in 1617, calculating sticks based on the geologia (lattice) multiplication method. In 1620 Edmund Gunter of London makes a straight logarithmic scale and performs multiplication and division on it with the use of a set of dividers, or calipers.

CIRCULAR SLIDE RULE


In about 1622 William Oughtred, an Anglican minister ... today recognized as the inventor of the slide rule, places two such scales side by side and slides them to read the distance relationships, thus multiplying and dividing directly. He also develops a circular slide rule.

Real Rocket Scientists used slide rules to send Man to the Moon - a Pickett model N600-ES was taken on the Apollo 13 moon mission in 1970.

The 17th century marked the beginning of the history of mechanical calculators, as it saw the invention of its first machines, including Pascal's calculator. In 1642, Blaise Pascal had invented a machine which he presented as being able to perform computations that were previously thought to be only humanly possible, but he wasn't successful in creating an industry.
Blaise Pascal invented a mechanical calculator with a sophisticated carry mechanism in 1642. After three years of effort and 50 prototypes he introduced his calculator to the public. He built twenty of these machines in the following ten years.This machine could add and subtract two numbers directly and multiply and divide by repetition. Since, unlike Schickard's machine, the Pascaline dials could only rotate in one direction zeroing it after each calculation required the operator to dial in all 9s and then (method of re-zeroing) propagate a carry right through the machine.

STEPPED RECKONER


In 1674, Gottfried Wilhelm Leibniz creates Stepped Reckoner. The device could add, subtract, multiply, and divide.

ARITHOMETER


Thomas’ arithmometer is a mechanical calculating machine designed to perform four basic arithmetical operations: addition, subtraction, multiplication and division. This machine was invented by the Frenchman Thomas de Colmar in 1820. This is the first calculating machine that was commercialized and manufactured in large quantities. The artithmometer practically dominated sales of calculating machines during the second part of 19th century. During all his life Thomas de Colmar was improving it. When he died in 1870, his son Thomas de Bojano, and later engineer Louis Payen, continued improvements and the production. 



A further step forward occurred in 1887 when Dorr. E. Felt’s US-patented key driven ‘Comptometer’ took calculating into the push button age. This machine, too, spurred a host of imitators.

The Curta calculator was developed in 1948 and, although costly, became popular for its portability. This purely mechanical hand-held device could do addition, subtraction, multiplication and division. By the early 1970s electronic pocket calculators ended manufacture of mechanical calculators, although the Curta remains a popular collectable item.



The Curta Calculator, resembling a pepper grinder with numbers, is highly sought after by collectors of slide rules and similar calculating devices. It was produced in two models:
  • Type I -Eight columns of numbers
  • Type II -Eleven columns of numbers
The Curta Calculator came in a can, usually black, two inches in diameter and four inches high. It was manufactured in Liechtenstein (which borders Switzerland).

The first mainframe computers, using firstly vacuum tubes and later transistors in the logic circuits, appeared in the 1940s and 1950s. This technology was to provide a stepping stone to the development of electronic calculators.



The Casio Computer Company, in Japan, released the Model 14-A calculator in 1957, which was the world's first all-electric (relatively) "compact" calculator. It did not use electronic logic but was based on relay technology, and was built into a desk.

Colossus was a specialised machine that basically performed “exclusive or” (XOR) Boolean algorithms.
However, it did this using hundred of thermionic valves as electronic on/off switches, as well as an electronic display.
The application of this technology to the world’s first general calculating computer had to wait until 1946 and the construction of the ENIAC(Electronic Numerical Integrator And Computer) as a completely digital artillery firing table calculator also capable of solving "a large class of numerical problems", including the four basic arithmetical functions.
ENIAC

ENIAC was 1,000 times faster than electro-mechanical computers and could hold a ten-digit decimal number in memory. But to do this required 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints. It weighed around 27 tonnes, took up 1800 square feet of floorspace and consumed as much power as a small town. Not exactly a desktop solution.

In 1961, First electronic calculators invented: Anita MK VII and Anita MK8. This was the world’s first all-electronic desktop calculator and it was developed in Britain by Control Systems Ltd., marketed under its Bell Punch and Sumlock brands.

ANITA used the same push button key layout as the company’s mechanical comptometers, but these were the only moving parts. All the rest was done electronically, using a mix of vacuum and cold cathode ‘Dekatron’ counting tubes.
Nevertheless, as the only electronic desktop calculator available, tens of thousands of ANITAs were sold worldwide up to 1964, when three new transistorised competitors appeared; the American Friden 130 series, the Italian IME 84, and the Sharp Compet CS10A from Japan.
Canon, Mathatronics, Olivetti, SCM (Smith-Corona-Marchant), Sony, Toshiba, and Wang.
Four of these Beatles-era transistorised calculators were especially significant, including Toshiba’s "Toscal" BC-1411 calculator, which was remarkable in using an early form of Random Access Memory (RAM) built from separate circuit boards.
The same year emerged the ELKA 22 designed by Bulgaria’s Central Institute for Calculation Technologies and built at the Elektronika factory in Sofia.
Built like a T-64 tank and weighing around 8 kg, this was the first calculator in the world to include a square root function.
Cal Tech

All electronic calculators to this point had been bulky and heavy machines, costing more than many family cars of the period.
However in 1967, Texas Instruments released their landmark "Cal Tech" prototype, a calculator that could add, multiply, subtract, and divide, and print results to a paper tape while being compact enough to be held in the hand.
1970 -- The first battery-operated "hand-held" calculators are sold. Most are too large to actually be considered "pocket calculators," but they are far smaller than anything seen before.
In mid-1970, Sharp begins to sell the QT-8B which, by using rechargeable batteries, is a portable version of their desk-top QT-8.
Canon's "Pocketronic" sales begin in the Fall of 1970 in Japan and February 1971 in the USA. Canon used Texas Instruments' ICs and thermal printer. Selling for just under $400, the "Pocketronic" was a four function, hand-held, printing calculator, with the only display being the printed tape running out of the side of the machine. It looks much like the "Cal-Tech" prototype (see 1965). The unit was rechargeable, used a disposable tape cartridge, and weighed 1.8 lbs.
Later that year, Sharp begins to market the EL-8, a "small" hand-holdable calculator with four function calculating power, 8 numeric tubes for a display, and rechargeable batteries. Redesigned from the QT-8 series, the unit is smaller and weighs 1.7 lbs.


Wednesday, November 16, 2016

VIDEO GAME




VIDEO GAME

If you are a hardcore gamer, can you imagine your life without Nintendo Wii, Xbox and Playstation?
Absolutely not. Let us have a view how these video games were invented and how it evolved over some decades.

In October 1958, Physicist William Higinbotham created what is thought to be the first video game at a Brookhaven National Laboratory open house. It was a very simple tennis game.

It took Higinbotham only a couple of hours to conceive the idea of a tennis game, and only a few days to put together the basic pieces. Having worked on displays for radar systems and many other electronic devices, Higinbotham had no trouble designing the simple game display.

Higinbotham made some drawings, and blueprints were drawn up. Technician Robert Dvorak spent about two weeks building the device. After a little debugging, the first video game was ready for its debut. They called the game Tennis for Two.



Players could turn a knob to adjust the angle of the ball, and push a button to hit the ball towards the other player. As long as they pressed the button when the ball was in their court, players couldn’t actually miss the ball, but if they hit it at the wrong time or hit it at the wrong angle, the ball wouldn’t make it over the net. Balls that hit the ground would bounce like a real tennis ball.

Tennis for Two had none of the fancy graphics video games use today. The cathode ray tube display simply showed a side view of a tennis court represented by just two lines, one representing the ground and a one representing the net. The ball was just a dot that bounced back and forth. Players also had to keep score for themselves.

Later in 1961, Steve Russell, a student at the Massachusetts Institute of Technology (MIT), creates Spacewar, the first interactive computer game. It runs on a Digital PDP-1 mainframe computer, and the graphics are made up of ASCII text characters.

RUSSELL'S SPACEWAR


But the first true video game wouldn't be invented until 1967 when an engineer named Ralph H. Baer created the first prototype of “Brown Box”, the world's first video game console.
The “Brown Box” was a vacuum tube-circuit that could be connected to a television set and allowed two users to control cubes that chased each other on the screen. 
The “Brown Box” was licensed to Magnavox, which released the system as the Magnavox Odyssey in 1972.



Baer, often known as the “Father of Video Games," was the first person to create a system that transformed electronic signals into pictures on a television screen via a raster pattern…or what we now know as a video game.
The original Magnavox Odyssey featured a few simple games, such as a chase game, checkers, and a shooting game using a rifle peripheral device. The system came with two paddle controllers, as well as a few other accessories usually associated with board games. It was a huge success, selling over 700,000 units in its first three years of production.

MAGNAVOX ODYSSEY

But these consoles are a very recent addition to the list of video games-related technologies that have developed over the years.
Perhaps, you might have heard your parents mention ‘Atari’? Ask them, and they will tell you about Pong, a game originally created by a company called Atari Incorporated, way back in 1972 — 44 years ago.
Pong was a two-dimensional tennis game and its creator was a man called Allen Alcorn. In those days, you could not simply buy a game and bring it home and play. There were places where these games were installed and they were coin-operated (arcade games). This meant that you had to put a coin in the machine to play the game!

In 1972, Atari (founded by Nolan Bushnell, the godfather of gaming) became the first gaming company to really set the benchmark for a large-scale gaming community.
Atari not only developed their games in-house, they also created a whole new industry around the “arcade,” and in 1973, retailing at $1,095, Atari began to sell the first real electronic video game Pong, and arcade machines began emerging in bars, bowling alleys and shopping malls around the world.
In 1975, Atari's Pong is released with help from Sears Roebuck, which finances the production of 150,000 units. It becomes the hottest selling Christmas present. Sears sells the product exclusively, with the Sears Tele-Games logo.
Gunfight, the first "computer" game is released. It is the first game to use a microprocessor instead of hardwired solid-state circuits.
In 1977, Atari introduces its first cartridge-based home video system called the Video Computer System which later becomes known as the Atari 2600. It retails for $249.95.
ATARI 2600

When it was released, the Atari VCS was only designed to play 10 simple challenge games, such as Pong, Outlaw and Tank. However, the console included an external ROM slot where game cartridges could be plugged in; the potential was quickly discovered by programmers around the world, who created games far outperforming the console’s original designed.
The integration of the microprocessor also led to the release of Space Invaders for the Atari VCS in 1980, signifying a new era of gaming — and sales: Atari 2600 sales shot up to 2 million units in 1980.
As home and arcade gaming boomed, so too did the development of the gaming community. The late 1970s and early 1980s saw the release of hobbyist magazines such as Creative Computing (1974), Computer and Video Games (1981) and Computer Gaming World (1981). These magazines created a sense of community, and offered a channel by which gamers could engage.
Nintendo, the company which eventually became a major player in the video gaming industry for the next three decades, delivered their first series of video game console from 1977 to 1979. The Color TV Game Series were only for sale in Japan. These consoles essentially followed in the footsteps of Atari and featured Pong-style games.
Once again, there were a few newcomers to the market but they were met with limited success. Bally Astrocade came about in 1977 and was celebrated for its superior graphic capabilities. For some reason, it did not last long. Mattel introduced its Intellivision console in 1979, which actually intimidated Atari 2600 with its exceptional capabilities.
The golden age of video gaming has arrived! With progressively advanced gaming technology,the 1980s was a period of genre innovation when the industry began experimenting with non-Pong games like fighting, platform, adventure and RPG games.
 It is also this era that we saw the release of all-time classic games such as Pac-man (1980), Mario Bros (1983), The Legend of Zelda (1986), Final Fantasy (1987), Golden Axe (1988), etc.
There was also a major shift from dedicated consoles (with built-in games) to cartridge-based video game systems. In the first few years of 1990s, there is a notable shift in the medium used for storing games from cartridges to compact discs.
There were increased capacities for video gaming, prompting as well a transition of 2D graphics to that of 3D. The first CD console was launched by Philips (1991) – the CD-i.
In 1992, NEC TurboGrafx-16 was upgraded to the TurboGrafx-CD to meet the demands of CD-based consoles. But again, it lost itself to Sega Genesis/MegaDrive with its latest add-on, the Sega CD.
The current generation of video game console only has room for three major competitors: Xbox 360, Sony Playstation 3 and Nintendo Wii. With full 1080p HD graphics for both the Xbox 360 and Playstation 3, and Wii’s innovative remote for sensing 3D movements, it seems that video gaming had indeed came a long, long way. 



Friday, April 3, 2015

TAJ MAHAL



The Taj Mahal of Agra is one of the Seven Wonders of the World. This ‘epitome of love’ is a magnificent creation built in the memory of Mughal Emperor Shah Jahan’s beloved wife Mumtaz Mahal.



The history of Taj Mahal adds a soul to its magnificence, a true soul filled with love, loss, remorse, and love again. Mughal Emperor Shah Jahan fell in love with Mumtaz Mahal at the age of 14. Five years later in the year 1612, they got married.

Mumtaz Mahal, an inseparable companion of Shah Jahan, died in 1631, while giving birth to their 14th child.

The construction of Taj Mahal started in the year 1631. It took approximately 22 years to build it making use of the services of 22,000 laborers and 1,000 elephants.

Masons, stonecutters, inlayers, carvers, painters, calligraphers, dome-builders and other artisans got engaged in its construction from the whole of the empire and also from Central Asia and Iran.

The monument was built entirely out of white marble, which was brought in from all over India and central Asia.


The entire Taj complex consists of five major constituents, namely Darwaza (main gateway), Bageecha (gardens), Masjid (mosque), Naqqar Khana (rest house) and Rauza (main mausoleum).

The main gateway is situated at the end of the long watercourse, bordered with Arabic calligraphy of verses from the Quran, made up of black stone and a domed central chamber.

The original door of the massive sandstone gateway was made out of solid silver.

The main tomb of Taj Mahal stands on a square platform raised 50 meter above the riverbank and was well-leveled with dirt to reduce seepage from the river.

The four minarets on each corner of this square are detached, facing the chamfered angles of the main and are deliberately kept at 137 feet to emphasize the beautiful and spherical dome that itself is 58 feet in diameter and 81 feet high.

The western side of the main tomb has the mosque and on the eastern side is the Naqqar Khana (rest/guest house), both made in red sandstone.


The two structures not only provide an architectural symmetry, but also make for an aesthetic color contrast. One can only marvel at the mosque and the rest house as despite being on the opposite ends, the two are mirror image of each other.

The Islamic style architecture of the garden has a well-defined meaning which symbolizes spirituality and according to the Holy Quran, the lush green, well watered is a symbol of Paradise in Islam. The raised pathways divide each of the four quarters into 16 flowerbeds with around 400 plants in each bed.

A shadowy burial crypt inside the Taj Mahal houses the tombs of Mumtaz Mahal and Shah Jahan himself, who were buried there after death. 

Above these tombs is the main chamber that has the false tombs and perforated marble screens used to transmit light into the burial chamber, typical of mausoleums of the Mughals.


Calligraphic inscriptions of the ninety nine names of Allah are also found on the sides of actual tomb of Mumtaz Mahal.

Thursday, April 2, 2015

BLOOD MOON TETRAD



A lunar eclipse occurs when the earth comes in between the sun and the moon. The sun’s rays are blocked from reaching the moon normally.

But some rays of sun curve around the earth, makes the moon to appear red during a total eclipse. This vivid colour total lunar eclipse is often referred to by NASA as a Blood Red Moon.



NASA confirmed that we have had "blood-red moons" on the first day of Passover and the first day of Sukkoth on back-to-back years seven times since 1 A.D. When four “blood-red moons” appears in close succession, NASA refers this as a tetrad.

The phenomenon of four consecutive blood red moons coinciding with Jewish feast days has only occurred ten times since 1 AD and only three times since 1492 AD. The three times are as follows:
•           Tetrad of 1493-1494
•           Tetrad of 1949-1950
•           Tetrad of 1967-1968

The religious teaching states that when four consecutive blood-red moons fall on Jewish feast days, a major event affecting the Jewish people will occur in close proximity to that time.



The Spanish Inquisition took place in 1492 just before the tetrad of 1493-1494
In 1492, the Spanish Inquisition was cruel beyond belief. Firstly Jews were forced to convert to Christianity then they were severely tortured to test the sincerity of their conversions. Once they confess, then they were burnt at the stake for not being true Catholics. 

The Nation of Israel reborn on May 14, 1948 just before the tetrad of 1949-1950
After the destruction of Jerusalem by the Romans in 70 AD, Jews were driven into exile. For the next 1,878 years, the Jewish people retained their identity but were shifted through the nations of the earth, having no permanent homeland.

After Hitler’s horrible holocaust during World War II, the Jews were finally granted a homeland by the nations of the world. On May 14, 1948, the modern state of Israel was born.

The City of Jerusalem was reunited during tetrad of 1967-1968
In the Old Testament God said that He would place His name in Jerusalem. During their 2,000 years of exile, the Jewish people turned their faces toward Jerusalem three times each day praying for the restoration of Jerusalem and the rebuilding of their temple in Jerusalem.

On June 7, 1967 the Jordanian attacked Israel and west Jerusalem. Israel counter-attacked thrown Jordan out of east Jerusalem and of Judea-Samaria, and back into its own land across the Jordan River. Jerusalem was undivided and under Jewish control for the first time after the destruction of Jerusalem by the Romans in 70 AD.



Four blood moons on Jewish feast days are getting ready to appear for the fourth time during 2014-2015. According to NASA, they will occur on:
•           April 15, 2014—Passover
•           October 8, 2014—Feast of Tabernacles
•           April 4, 2015—Passover
•           September 28, 2015—Feast of Tabernacles

Some prophecy teachers are declaring that this tetrad is signalling towards something ready to happen, which will change the world forever. Let us see what will happen in this Tetrad. Hope for something good…


Saturday, March 28, 2015

COMPUTER PRINTER

In 1938 Xerography, a dry printing process was invented by the American inventor Chester Carlson.

The word ‘Xerography’ comes from the Greek word which means ‘dry writing’. It was the foundation technology for copiers and laser printers.

Carlson applied for patent in 1939 and in 1942 the patent was granted to him.


But he was not successful to catch the interest of companies towards his invention. Later on, Carlson succeeded to negotiate commercial rights of his invention to Haloid Company in 1947.

This was the biggest deal of the life both for Carlson and for the company Haloid, which became one of biggest companies in the world due to this invention. Later on this company was renamed as ‘Xerox’.

In 1967 a young researcher in Xerox's Webster Research Center in Rochester, Gary K. Starkweather was sitting in his lab thinking instead of copying someone else's original, if we use a computer to generate the original and here only the idea of the laser printer was born.

At that time, the lasers were expensive devices, but convinced that the cost of lasers would drop over time and also there was a market for laser printing technology, Starkweather stuck to his guns.

His ideas were not meeting the requirements from Xerox management. Hewas told to stop working on the laser printer project. But he couldn't.

He just go through with his idea ignoring all ifs and but. He convinced people to get different parts for building it. The prototype was ready in 1969. It was built by modifying an existing xerographic copier.

Starkweather disabled the imaging system and created a spinning drum with 8 mirrored sides, with a laser focused on the drum. Light from the laser would bounce off the spinning drum, sweeping across the page as it moved through the copier.

The hardware was completed in just two weeks, but the computer interfacing and software took almost 3 months to get completed.

Printers were now a pillar of the company's growth strategy. Starkweather's drive to create the laser printer eventually transformed a small copier company into one of the world's imaging powerhouses, and revolutionized the computer printing industry.

When Xerox build the Palo Alto Research Center (PARC) in California in 1970, Starkweather came for salvation. 

Out of hostile territory,  he was finally given the freedom to conduct his research without fear of retribution. Starkweather went to work on building the laser printer.

In 1971, just nine months after joining PARC, Starkweather completed the first working laser printer.
He named it as ‘SLOT’, an acronym for Scanned Laser Output Terminal.

The digital control system and character generator for the printer were developed by Butler Lampson and Ronald Rider in 1972.

 The combined efforts resulted in a printer named EARS (Ethernet, Alto, Research character generator, Scanned laser output terminal).

 The EARS printer was used with the Alto computer system network and subsequently became the Xerox 9700 laser printing system.

Xerox 9700 was introduced in 1977, it was the industry's first commercial laser printer.
It was a wild success, few customers would produce the 200000 to 300000 prints per month needed for the unit to be profitable.

Starkweather shifted his research onto personal laser printers, and again worked against Xerox.
Xerox was a company that liked large, fast laser printers. They saw departmental units as the profit center for laser printer technology.

Xerox failed to realize that the profit wasn't in the printer but in the ink toner and the paper. As a result, the company was beaten up by Hewlett-Packard, which introduced the first personal laser printer in 1980.

Xerox always encouraged new ideas but never really liked to pursue them for very long. Things like Postscript, the laser printer, the personal computer, the bitmapped screen, the iconic interface, Ethernet, packet switching, all of this came out of PARC. And none of it, ended up as a product of Xerox.

In 1985, Office laser printers become available with high quality text and graphics. One of them is the Apple LaserWriter, a PostScript laser printer.

 HP LaserJet is introduced around the same time and uses the same Canon engine as the LaserWriter.
In 1987 Starkweather however left the company after 24 years of service. Following a 10-year stint at Apple Computer, Starkweather joined Microsoft Research in 1997. These days, his main area of research is display technology.

During mid-1990s, Xerox Majestik offers comparable image quality and colour to Canon CLC range and the color laser printing market becomes competitive in the market.
 



Tuesday, March 17, 2015

CAPACITOR

A capacitor is a device for temporarily storing electric charge.

In October 1745, Ewald Georg Von Kleist of Pomerania in Germany found that charge could be stored by connecting a generator by a wire to a volume of water in a hand-held glass jar.

Von Kleist's hand and the water acted as conductors and the jar as a dielectric. Von Kleist found that touching the wire resulted in a spark even after removing the generator.


In a letter describing the experiment, he said "I would not take a second shock for the kingdom of France."

In 1746, the Leyden jar was invented by Pieter van Musschenbroek at the University of Leyden in Holland. It was a glass jar wrapped inside and out by a thin metal foil.

The two layers of electrically conducting material that is metal foil here were separated by layers of a non-conducting material that was glass in the case of the Leyden jar, but it can also be wax, mica, oil, paper, tantalum, plastic, ceramic material, or even air.


The outer foil was connected to the ground, and the inner foil was connected to a source of electricity such as an electrostatic generator.

The plates will become charged, one positively and one negatively. If the externally applied voltage is then removed, the plates of the capacitor remain charged, and the presence of the electric charge induces an electrical potential between the plates.

 Daniel Gralath was the first scientist to combine several Leyden jars in parallel into a "battery" to increase the charge storage capacity.

Benjamin Franklin checked the Leyden jar, and proved that the charge was stored on the glass, not in the water as it was assumed.

He used a Leyden jar to store electricity from lightning in his famous kite flying experiment in 1752. By doing so he proved that lightning was really electricity.

He deviced the idea of a parallel or flat plate capacitor & developed the first flat plate capacitor called the Franklin Square.

Leyden jars began to be made by coating the inside and outside of jars with metal foil, leaving a space at the mouth to prevent arcing between the foils.

The earliest unit of capacitance was the 'jar', equivalent to about 1 Nano farad.

Years later, Michael Faraday experimented and made the first practically viable capacitor. Faraday’s pioneering role in capacitor technology has been honoured by naming the SI unit of Capacitance as ‘Farad’.

Leyden jar or flat glass plate construction was used until about 1900.

The invention of wireless (radio) created a demand for standard capacitors, and the steady move to higher frequencies required capacitors with lower inductance.


A flexible dielectric sheet such as oiled paper sandwiched between sheets of metal foil, rolled or folded into a small package were constructed.

Early capacitors were also known as condensers, this term is still used occasionally now.

It was coined by Alessandro Volta in 1782.

 It was derived from the Italian word “condensatore”, with reference to the device's ability to store a higher density of electric charge than a normal isolated conductor.