X- Ray Diffraction

Diffraction and Bragg's Law

Diffraction occurs as waves interact with a regular structure whose repeat distance is about the same as the wavelength. The phenomenon is common in the natural world, and occurs across a broad range of scales. For example, light can be diffracted by a grating having scribed lines spaced on the order of a few thousand angstroms, about the wavelength of light.

It happens that X-rays have wavelengths on the order of a few angstroms, the same as typical interatomic distances in crystalline solids. That means X-rays can be diffracted from minerals which, by definition, are crystalline and have regularly repeating atomic structures.

When certain geometric requirements are met, X-rays scattered from a crystalline solid can constructively interfere, producing a diffracted beam. In 1912, W. L. Bragg recognized a predicatable relationship among several factors.

1. The distance between similar atomic planes in a mineral (the interatomic spacing) which we call the d-spacing and measure in angstroms.

2. The angle of diffraction which we call the theta angle and measure in degrees. For practical reasons the diffractometer measures an angle twice that of the theta angle. Not surprisingly, we call the measured angle '2-theta'.

3. The wavelength of the incident X-radiation, symbolized by the Greek letter lambda and, in our case, equal to 1.54 angstroms.

The Diffractometer

A diffractometer can be used to make a diffraction pattern of any crystalline solid. With a diffraction pattern an investigator can identify an unknown mineral, or characterize the atomic-scale structure of an already identified mineral.

There exists systematic X-ray diffraction data for thousands of mineral species. Much of these data are gathered together and published by the JCPDS-International Centre for Diffraction Data.

The diffractometer in the IPFW Geosciences Department is a Philips APD3520 built in 1986. It consists of several parts.

· The chiller provides a source of clean water to cool the X-ray tube.The regulator smooths our building current to provide a steady and dependable source of electricity to the diffractometer and its peripherals.

· The computer sends commands to the diffractometer and records the output from an analysis. We are currently using a 486-100 running DR-DOS7 to run the diffractometer, and provide interfacing with this web page. We process most of the information digitally, although we can make hardcopy analog patterns directly on the;

· Strip-chart recorder.

· The theta compensating slit collimates the X-rays before they reach the sample.

· Scintillation counter which measures the X-ray intensity. It is mounted on the;

· Goniometer which literally means angle-measuring device. The goniometer is motorized and moves through a range of 2-theta angles. Because the scintillation counter is connected to the goniomter we can measure the X-ray intensity at any angle to the specimen. That's how we determine the 2-theta angles for Braggs's Law.

Diffraction Patterns

A diffraction pattern records the X-ray intensity as a function of 2-theta angle. All the diffraction patterns you'll see on this web site were prepared as step-scans. To run a step-scan we mount a specimen, set the tube voltage and current, and enter the following parameters:

--A starting 2-theta angle.
--A step-size (typically 0.005 degrees).
--A count time per step (typically 0.05-1 second).
--An ending 2-theta angle.

Once started, the goniometer moves through its range, stopping at each step for the alotted time. The X-ray counts at each step are saved to a file on the computer. Once finished, the data are smoothed with a weighted moving average and a diffractogram like the one below is printed or displayed.

Consider the following areas on the diffractogram.

A. The diffraction pattern is labelled with the sample name and other information pertinent to the experiment. This happens to be a pattern of ground calcite from the France Stone Quarry in Fort Wayne, Indiana. The sample was randomly mounted using the backpack technique. The diffraction pattern was prepared on March 24, 1993. The diffractometer was running at 40 kv and 30 ma. Steps were in increments of 0.005 degrees, and counts were collected for 0.25 seconds at each step. The data were smoothed with a 15-pt (weighted, moving average) filter.

B. The vertical axis records X-ray intensity. The horizontal axis records angles in degrees 2-theta. Low angles (large d-spacings) lie to the right.

C. This is one of the X-ray peaks. It happens to be the one with the smallest angle which I measured as 23.04 degrees. Solving Bragg's Law (with n=1 and wavelength=1.54 ang) we find that 23.04 degrees 2-theta corresponds to a d-spacing of 3.86 angstrom.

D. This is another peak picked for no special reason. I measured the peak at 39.37 degrees 2-theta. This corresponds to a d-spacing of 2.287 angstrom.

E. This is the largest peak on the pattern. It actually extends several times the height of this image. Many factors affect the intensity of a given peak. Some of these factors are intrinsic to the mineral under study; some of these factors are peculiar to the way a specimen is mounted in the diffractometer. (The random/backpack mounting method limits, but does not eliminate, these peculiarities). You can see a partial list of calcite peaks.

Laser, action and einstein’s theory of laser,type,its applications in industry and magnetic field.

Laser, action and einstein’s theory of laser,type,its applications in industry and magnetic field.

Contents

1.introduction

2.what is laser

3.types of laser

4.overview

5.characteristic of laser

6.operation

7.laser devices

8. Laser components

9.einstein theory of laser

10.application

11. reference

Introduction

The word Laser is an acronym for light amplification by stimulated emission of radiation.A laser is a device that creates and amplifies a narrow, intense beam of coherent light. Atoms emit radiation,we see it every day when the "excited" neon atoms in a neon sign emit light. Normally, they radiate their light in random directions at random times. The result is incoherent light. The trick in generating coherent light of a single or just a few frequencies going in one precise direction is to find the right atoms with the right internal storage mechanisms and create an environment in which they can all cooperate to give up their light at the right time and all in the same directi

The ruby laser, a simple and common type, has a rod-shaped cavity made of a mixture of solid aluminum oxide and chromium. The output is in pulses that last approximately 500 microseconds each. Pumping is done by means of a helical flash tube wrapped around the rod. The output is in the red visible range.

The helium-neon laser is another popular type, favored by electronics hobbyists because of its moderate cost. As its name implies, it has a cavity filled with helium and neon gases. The output of the device is bright crimson. Other gases can be used instead of helium and neon, producing beams of different wavelengths. Argon produces a laser with blue visible output. A mixture of nitrogen, carbon dioxide, and helium produces IR output.

Lasers are one of the most significant inventions developed during the 20th century. They have found a tremendous variety of uses in electronics, computer hardware, medicine, and experimental science.

Overview

Wavelengths of commercially available lasers. Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser material (see the figure description for details). Most of the data comes from Weber's book Handbook of laser wavelengths [1], with newer data in particular for the semiconductor lasers.

Types of Laser

· According to their sources:

1.Gas Lasers

2. Crystal Lasers

3.Semiconductors Lasers

4.Liquid Lasers

· According to the nature of emission:

1.Continuous Wave

2.Pulsed Laser

· According to their wavelength:

1. Visible Region

2. Infrared Region

3. Ultraviolet Region

4.Microwave Region

5.X-Ray Region

Characteristics of Laser

Highly Monochromatic:

* Laser ray is highly pure beam of light with respect to the wavelength and the frequency of the photons forming it.

Highly Directional

* laser beam is highly intense and very narrow beam this is because its divergence is very small.

* Laser beam transfers in straight lines approximately parallel to each other.

Highly Coherent

* The laser photons are coherent,in phase and have the same direction.

Fundamental of Laser Operation

1.Excitation of the atom:

* The Ground level (E1): It is the nearest energy level to the nucleus. e.g. the ground level for Hydrogen atom is (K) level while that for (cr) atom is (N).

* The excited levels: They are levels whose energies are higher than the ground levels.

1) Transition of an atom from lower energy level (E1) to the higher energy level (E2) requires absorption of a quantized amount of energy equals the difference in energy of these two levels.

2) Transition of the atom from the higher energy level (E2) to the lower energy (E1) is accompanied by the emission of an amount of energy E= E2-E1 in the form of light quantum (photon) of energy (h.v)

E=h.v=E2-E1

v=E/h=(E2-E1)/h

where (v) is the frequency of the emitted radiation.

In 1917 , Einstein showed that emission can exist by one of the two following ways:

1) Spontaneous emission:

It takes place when the atom moves of its own from the higher energy level (E2) to the lower energy level (E1) emitting a photon of energy (h.v). Therefore the spontaneous transition occurs by its own without control i.e.there is no relation between the incident and emitted photons with respect to their direction or phase. so the emitted light photons are incoherent. The spontaneous emission takes place in all traditional sources e.g. neon lamp, sodium lamp-----etc.

2) Stimulated emission:

It takes place when a photon of energy (h.v) passes by an excited atom so the atom is stimulated to emit a photon having the same energy , frequency and phase of the incident photon. Therefore we obtain two identical photons which are in the same direction. And these two identical photons stumuli another two excited atoms thus we obtain (4) coherent photons and so on.

The stimulated emission is characterized by:

The emission of new photon in addition of the initial one.

The photon in the stimulated emission , has the same energy of the initial photon , consequently it must have the same frequency and wavelength.

The waves associating the two photons initial and that produced in the stimulated emission are in phase.

The conditions needed to obtain stimulated emission(Laser):

Exciting a large number of atoms to exist in the higher energy level.

Doing enough arrangements to enable most of the emitted photons to emerge in the same direction.

Laser Devices

This section discusses the historical evolution from microwave lasers to optical lasers and finally to xray lasers.

Microwave Laser

Optical Laser

Gas Dynamic Laser

X-ray Laser

Plasma Laser .

Lasing in Two, Three, and Four-level Atoms

For the sake of our studies, let's first consider a laser medium whose atoms have only two energy states: a ground state and one excited state. In such an idealized atom the only possible transitions are excitation from the ground state to the excited state, and de-excitation from the excited state back into ground state. Could such an atom be used to make a laser?

There are several important conditions that our laser must satisfy. First of all, the light that it produces must be coherent. That is to say, it must emit photons that are in-phase with one another. Secondly, it should emit monochromatic light, i.e. photons of the same frequency (or wavelength). Thirdly, it would be desirable if our laser's output were collimated, producing a sharply defined "pencil-like" beam of light (this is not crucial, but clearly a desirable condition). Lastly, it would also be desirable for our laser to be efficient, i.e. the higher the ratio of output energy - to - input energy, the better.

Let us begin by examining the requirements for our first condition for lasing, coherence. This condition is satisfied only when the lasing transition occurs through stimulated emission. As we have already seen, stimulated emission produces identical photons that are of equal energy and phase and travel in the same direction. But for stimulated emission to take place a "passer-by" photon whose energy is just equal to the de-excitation energy must approach the excited atom before it de-excites via spontaneous emission. Typically, a photon emitted by the spontaneous emission serves as the seed to trigger a collection of stimulated emissions. Still, if the lifetime of the excited state is too short, then there will not be enough excited atoms around to undergo stimulated emission. So, the first criteria that we need to satisfy is that the upper lasing state must have a relatively long lifetime, otherwise known as a meta-stable state, with typical lifetimes in the milliseconds range. In addition to the requirement of a long lifetime, we need to ensure that the likelihood of absorption of the "passer-by" photons is minimized. This likelihood is directly related to the ratio of the atoms in their ground state versus those in the excited state. The smaller this ratio, the more likely that the "passer-by" photon will cause a stimulated emission rather than get absorbed. So, to satisfy this requirement, we need to produce a population inversion: create more atoms in the excited state than those in the ground state.

Achieving population inversion in a two-level atom is not very practical. Such a task would require a very strong pumping transition that would send any decaying atom back into its excited state. This would be similar to reversing the flow of water in a water fall. It can be done, but is very energy costly and inefficient. In a sense, the pumping transition would have to work against the lasing transition.

It is clear, from the above diagram, that in the two-level atom the pump is, in a way, the laser itself! Such a two-level laser would work only in jolts. That is to say, once the population inversion is achieved the laser would lase. But immediately it would end up with more atoms in the lower level. Such two-level lasers involve a more complicated process. We will see, in later material, examples of these in the context of excimer lasers, which are pulsed lasers. For a continuous laser action we need to consider other possibilities, such as a three-level atom. In fact, the first laser that was demonstrated to operate was a three-level laser, Maiman's ruby laser.

In the above diagram of a three level laser the pump causes an excitation from the ground state to the second excited state. This state is a rather short-lived state, so that the atom quickly decays into the first excited level. [Decays back to the ground state also occur, but these atoms can be pumped back to the second excited state again.] The first excited state is a long-lived (i.e. metastable) state which allows the atom to "wait" for the "passer-by" photon while building up a large population of atoms in this state. The lasing transition, in this laser, is due to the decay of the atom from this first excited metastable state to the ground state. If the number of atoms in the ground state exceeds the number of atoms that are pumped into the excited state, then there is a high likelihood that the "lasing photon" will be absorbed and we will not get sustained laser light. The fact that the lower lasing transition is the ground state makes it rather difficult to achieve efficient population inversion. In a ruby laser this task is accomplished by providing the ruby crystal with a very strong pulsating light source, called a flash lamp. The flash lamp produces a very strong pulse of light that is designed to excite the atoms from their ground state into any short-lived upper level. In this way the ground state is depopulated and population inversion is achieved until a pulse of laser light is emitted. In the ruby laser the flash lamp light lasts for about 1/1000 of a second (1 ms) and can be repeated about every second. The duration of the laser pulse is shorter than this, typically 0.1 ms. In some pulsed lasers the pulse duration can be tailored using special methods to be much shorter than this, down to about 10 fs (where 1 fs = 10-15 s or one thousandth of a millionth of a millionth of a second). So, the output of a three-level laser is not continuous, but consists of pulses of laser light. To achieve a continuous beam of laser light a four-level laser is required.

Here, the lower laser level is not the ground state. As a result, even a pump that may not be very efficient could produce population inversion, so long as the upper level of the laser transition is longer lived than the lower level. Of course, all attempts are made to design a pump that maximizes the number of excited atoms. A typical four-level laser is the helium-neon (He-Ne) gas laser. In these lasers electric pumping excites helium atoms to an excited state whose energy is roughly the same as the upper short-lived state in the neon atom. The sole purpose of the helium atoms is to exchange energy with neon atoms via collisional excitation. As it turns out, this is a very efficient way of getting neon atoms to lase.

Laser components

All lasers have threeprimary components:

Ø Medium

Ø Pump

Ø Resonant Cavity

The laser medium can be gaseous, liquid, or a solid. These could include atoms, molecules, or collections of atoms that would be involved in a laser transition. Typically, a laser is distinguished by its medium, even though two lasers using different media may have more in common than two which have similar media.

There are three different laser pumps: electromagnetic, optical, and chemical. Most lasers are pumped electro-magnetically, meaning via collisions with either electrons or ions. Dye lasers and many solid state lasers are pumped optically; however, solid state lasers are typically pumped with a broad band (range of wavelengths) flash-lamp type light source, or with a narrow band semiconductor laser. Chemically pumped lasers, using chemical reactions as an energy source, are not very efficient. So far, these lasers have been made to work not so much for their usefulness as for their curious operation.

Up to now in our discussion of laser theory we have not really seen how the beam is generated. We know that photons emitted by stimulated emission travel coherently in the same direction, but what is it that defines the beam direction and what allows the intensity of the laser light to get large? The answer to these two questions is coupled together in the resonant cavity. Laser resonant cavities usually have two flat or concave mirrors, one on either end, that reflect lasing photons back and forth so that stimulated emission continues to build up more and more laser light. The "back" mirror is made as close to 100% reflective as possible, while the "front" mirror typically is made only 95 - 99% reflective so that the rest of the light is transmitted by this mirror and leaks out to make up the actual laser beam outside the laser device.

The resonant cavity thus accounts for the directionality of the beam since only those photons that bounce back and forth between the mirrors lead to amplification of the stimulated emission. Once the beam escapes through the front mirror it continues as a well-directed laser beam. However, as the beam exits the laser it undergoes diffraction and does have some degree of spreading. Typically this beam divergence is as small as 0.05o but even this small amount will be apparent if the beam travels long distances.

Even more, the resonant cavity also accounts for the amplification of the light since the path through the laser medium is elongated by repeated passes back and forth. Typically this amplification grows exponentially, similar to the way compound interest works in a bank. The more money in your bank account, with compound interest, the faster you earn more interest dollars. Similarly, the more photons there are to produce stimulated emission, the larger the rate at which new coherent photons are produced. The term used for laser light is gain, or the number of additional photons produced per unit path length.

The last question to address in this section is: why is the resonant cavity called by that name? What does resonance have to do with having mirrors on either end of a region containing the laser medium? Recall that when we discussed resonance on a string, we spoke about the wave traveling one way along the string (say to the right) interfering with the wave reflected at the end traveling back to the left. At a resonant frequency, there are points at which the two waves exactly add or cancel all the time, leading to a standing wave. At other frequencies the waves will randomly add or cancel and the wave will not have a large amplitude. The case of a light wave traveling back and forth in the resonant cavity is exactly analogous in that only at certain resonant frequencies will the light wave be amplified. The required condition is easy to see. The mirror separation distance, L, must be equal to a multiple of half a wavelength of light, just as we saw in the case of a string. In symbols, we have that L = nl/2, where l is the wavelength of the light and n is some integer. In the case of light, because of the small wavelength n is a very large number, implying that there are a huge number of resonant frequencies. On the other hand, only those resonant frequencies that are amplified by the laser medium will have large amplitudes and so usually there are only a few so-called laser modes or laser resonant frequencies present in the light from a laser, as shown in the figure.

Laser Components

Einstein Theory Of Laser

Albert Einstein in his paper in 1917 gave the principle for the laser based on the coefficient of the absorption, spontaneous emission and stimulated emission.

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Applications of Laser

The laser has contributed to humanity as a powerful scientific tool for expanding human knowledge and in its many applications that help people directly. It has been put to work in a vast range of applications and has assumed many forms.

In communications:

Engineers recognized the potential of the laser to replace electrical transmission over copper wires, but how to transmit the pulses presented enormous problems. In 1960, Some Scientists transmitted pulses of light a distance of 25 miles the laser produced an intense and extremely narrow beam of light that was more than a million times brighter than the sun.

In Search of a medium:

Unfortunately, Laser beam is easily affected by atmospheric conditions, such as rain, fog, low clouds, and objects in the air, like birds. Scientists suggested a number of novel schemes to protect the light from interference, including shielding it in metal tubes and using specially designed mirrors and thermal gas lenses to navigate around bends.

In Telecommunications:

Telecommunications relies today on photons, as tiny semiconductor lasers transmit light pulses carrying billions of bits of information per second over glass fibers. Wavelength division multiplexing technology uses various wavelengths, or colors, of light to transmit trillions of bits simultaneously over a single fiber.

In medicine:

Laser is used in the field of medicine after inventing the carbon dioxide laser, which soon permitted surgeons to perform highly intricate surgery using photons, rather than scalpels, to both operate on and cauterize wounds. Lasers today can be inserted inside the body, performing operations that a few years ago were almost impossible to perform.

Today, lasers are also used in a wide range of applications in medicine, manufacturing, the construction industry, surveying, consumer electronics, scientific instrumentation, and military systems. Literally billions of lasers are at work today. They range in size from tiny semiconductor devices no bigger than a grain of salt to high-power instruments as large as an average living room.

Reference

1.Newage publisher pvt.ltd, laser and nonlinear optics,p.b.laud

2. Macmillan publisher ,laser theory of application,k dhyacagran,a.k.ghatak

3. University pulisher ,laser ,e.a siegman

4. http://www.nobel.org.

5. http://en.wikipedia.org/wiki/Laser

6.http://science.howstuffworks.com/laser.htm

7. http://www.scribd.com/doc/23886162/Laser-Action-Einstein-Theory-of-Laser-Types-Applications-in-Industry

8. http://technicalstudies.youngester.com/2010/06/memory-key-in-steampunk-style-0.html

To Download The Research paper with images and proper format GOTO> http://tyro.in

Microprocessors

A microprocessor incorporates most or all of the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC, or microchip). Computer processors were for a long period constructed out of small and medium-scale ICs containing the equivalent of a few to a few hundred transistors. The integration of the whole CPU onto a single chip therefore greatly reduced the cost of processing capacity. From their humble beginnings, continued increases in microprocessor capacity have rendered other forms of computers almost completely obsolete with one or more microprocessor as processing element in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.

contents-

1. about microprocessor

2. History about it

3. How it work

4. Uses of it

5. Types of it

6. About Intel 8085, 8086

7. Its application

8. References.

history of microprocessor

In November, 1971, a company called Intel publicly introduced the world's first single chip microprocessor, the Intel 4004 (U.S. Patent #3,821,715), invented by Intel engineers Federico Faggin, Ted Hoff, and Stan Mazor. After the invention of integrated circuits revolutionized computer design, the only place to go was down in size that is. The Intel 4004 chip took the integrated circuit down one step further by placing all the parts that made a computer think on one small chip. Programming intelligence into inanimate objects had now become possible.

# History about Intel

In 1968, Bob Noyce and Gordon Moore were two unhappy engineers working for the Fairchild Semiconductor Company who decided to quit and create their own company at a time when many Fairchild employees were leaving to create start-ups. People like Noyce and Moore were nicknamed the "Fairchildren".

Bob Noyce typed himself a one page idea of what he wanted to do with his new company, and that was enough to convince San Francisco venture capitalist Art Rock to back Noyce's and Moore's new venture. Rock raised $2.5 million dollars in less than 2 days.

THE INTEL 4004 MICROPROCESSOR

The 4004 was the world's first universal microprocessor. In the late 1960s, many scientists had discussed the possibility of a computer on a chip, but nearly everyone felt that integrated circuit technology was not yet ready to support such a chip. Intel's Ted Hoff felt differently; he was the first person to recognize that the new silicon-gated MOS technology might make a single-chip CPU (central processing unit) possible.

Hoff and the Intel team developed such an architecture with just over 2,300 transistors in an area of only 3 by 4 millimeters. With its 4-bit CPU, command register, decoder, decoding control, control monitoring of machine commands and interim register, the 4004 was one heck of a little invention. Today's 64-bit microprocessors are still based on similar designs, and the microprocessor is still the most complex mass-produced product ever with more than 5.5 million transistors performing hundreds of millions of calculations each second - numbers that are sure to be outdated fast.

How Microprocessors Work

The computer you are using to read this page uses a microprocessor to do its work. The microprocessor is the heart of any normal computer, whether it is a desktop machine, a server or a laptop. The microprocessor you are using might be a Pentium, a K6, a PowerPC, a Sparc or any of the many other brands and types of microprocessors, but they all do approximately the same thing in approximately the same way.

A microprocessor -- also known as a CPU or central processing unit -- is a complete computation engine that is fabricated on a single chip. The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very powerful -- all it could do was add and subtract, and it could only do that 4 bits at a time. But it was amazing that everything was on one chip. Prior to the 4004, engineers built computers either from collections of chips or from discrete components (transistors wired one at a time). The 4004 powered one of the first portable electronic calculators.

Microprocessor performance

The number of transistors available has a huge effect on the performance of a processor. As seen earlier, a typical instruction in a processor like an 8088 took 15 clock cycles to execute. Because of the design of the multiplier, it took approximately 80 cycles just to do one 16-bit multiplication on the 8088. With more transistors, much more powerful multipliers capable of single-cycle speeds become possible.

More transistors also allow for a technology called pipelining. In a pipelined architecture, instruction execution overlaps. So even though it might take five clock cycles to execute each instruction, there can be five instructions in various stages of execution simultaneously. That way it looks like one instruction completes every clock cycle.

^{64-bit Microprocessors}

Sixty-four with us since 1992, and in the 21st century they have started to become mainstream. -bit processors have been Both Intel and AMD have introduced 64-bit chips, and the Mac G5 sports a 64-bit processor. Sixty-four-bit processors have 64-bit ALUs, 64-bit registers, 64-bit buses and so on.

One reason why the world needs 64-bit processors is because of their enlarged address spaces. Thirty-two-bit chips are often constrained to a maximum of 2 GB or 4 GB of RAM access. That sounds like a lot, given that most home computers currently use only 256 MB to 512 MB of RAM. However, a 4-GB limit can be a severe problem for server machines and machines running large databases. And even home machines will start bumping up against the 2 GB or 4 GB limit pretty soon if current trends continue. A 64-bit chip has none of these constraints because a 64-bit RAM address space is essentially infinite for the foreseeable future -- 2^64 bytes of RAM is something on the order of a billion gigabytes of RAM.

With a 64-bit address bus and wide, high-speed data buses on the motherboard, 64-bit machines also offer faster I/O (input/output) speeds to things like hard disk drives and video cards. These features can greatly increase system performance^.

Use of microprocessor

The use of microprocessors was limited to task-based operations specifically required for company projects such as the automobile sector. The concept of a 'personal computer' was still a distant dream for the world and microprocessors were yet to come into personal use. The 16 bit microprocessors started becoming a commercial sell-out in the 1980s with the first popular one being TMS9900

the of Texas Instruments.

Intel developed the 8086 which still serves as the base model for all latest advancements in the microprocessor family. It was largely a complete processor

integrating all the required features in it. 68000 by Motorola was one of the first microprocessors to develop the concept of microcoding in its instruction set. They were further developed to 32 bit architectures. Similarly, many players like Zilog, IBM and Apple were successful in getting their own products in the market. However, Intel had a commanding position in the market right through the microprocessor era.

The 1990s saw a large scale application of microprocessors in the personal computer applications developed by the newly formed Apple, IBM and Microsoft corporation. It witnessed a revolution in the use of computers, which by then was a household entity.

This growth was complemented by a highly sophisticated development in the commercial use of microprocessors. In 1993, Intel brought out its 'Pentium Processor' which is one of the most popular processors in use till date. It was followed by a series of excellent processors of the Pentium family, leading into the 21st century. The latest one in commercial use is the Pentium Dual Core technology and the Xeon processor. They have opened up a whole new world of diverse

Intel 8085

Produce: From 1977 to 1990s

Common manufacturer(s) Intel and several others

Max. CPU clock rate 3,5 and 6 MHz

Instruction set pre x86

Package(s) 40 pin DIP

The Intel 8085 is an 8-bit microprocessor introduced by Intel in 1977. It was binary-compatible with the more-famous Intel 8080 but required less supporting hardware, thus allowing simpler and less expensive microcomputer systems to be built.

The "5" in the model number came from the fact that the 8085 required only a +5-volt (V) power supply rather than the +5V, -5V and +12V supplies the 8080 needed. Both processors were sometimes used in computers running the CP/M operating system, and the 8085 later saw use as a microcontroller.

The 8085 had a very long life as a controller. Once designed into such products as the DECtape controller and the VT100 video terminal in the late 1970s, it continued to serve for new production throughout the life span of those products (generally many times longer than the new manufacture lifespan of desktop computers).

The 8085 was a binary compatible follow up on the 8080, the successor to the original Intel 8008. The 8080 and 8085 used the same basic instruction set as the 8008 (developed by Computer Terminal Corporation) and they were source code compatible with their predecessor. However, the 8080 added several useful and handy 16-bit operations above the 8008 instruction set: The 16-bit stack pointer in the 8080 enabled the stack to hold parameters and local data as well as return addresses, just like in larger CPUs, and the single 8008 addressing mode via the HL register pair was complemented by direct addressing for 8/16-bit loads and stores. The ability to employ BC and DE as two additional 16-bit pointers was also new in the 8080. The 8085 added only a few relatively minor instructions above the 8080 set.

Intel 8086

The 8086 (also called iAPX86) is a 16-bit microprocessor chip designed by Intel, which gave rise to the x86 architecture; development work on the 8086 design started in the spring of 1976 and the chip was introduced to the market in the summer of 1978. The Intel 8088, released in 1979, was a slightly modified chip with an external 8-bit data bus (allowing the use of cheaper and fewer supporting logic chips and is notable as the processor used in the original IBM PC.

Background

In 1972, Intel launched the 8008, the first 8-bit microprocessor. It implemented an instruction set designed by Datapoint corporation with programmable CRT terminals in mind, that also proved to be fairly general purpose.

Two years later, in 1974, Intel launched the 8080, employing the new 40-pin DIL packages originally developed for calculator ICs to enable a separate address bus. It had an extended instruction set that was source- (not binary-) compatible with the 8008 and also included some 16-bit instructions to make programming easier. The 8080 device.

The 8086 project started in may 1976 and was originally intended as a temporary substitute for the ambitious and delayed iAPX 432 project. It was an attempt to draw attention from the less-delayed 16 and 32-bit processors of other manufacturers (such as Motorola, Zilog, and National Semiconductor) and at the same time to counter the threat from the Zilog Z80 (designed by former Intel employees), which became very successful. Both the architecture and the physical chip were therefore developed rather quickly by a small group of people, and using the same basic microarchitecture elements and physical implementation techniques as employed for the slightly older 8085 (and for which the 8086 also would function as a continuation).

The first revision of the instruction set and high level architecture was ready after about three months, and as almost no CAD-tools were used, four engineers and 12 layout people were simultaneously working on the chip. The 8086 took a little more than two years from idea to working product, which was considered rather fast for a complex design in 1976-78.

The 8086 was sequenced using a mix of random logic and microcode and was implemented using depletion load nMOS circuitry with approximately 20,000 active transistors (29,000 counting all ROM and PLA sites). It was soon moved to a new refined nMOS manufacturing process called HMOS (for High performance MOS) that Intel originally developed for manufacturing of fast static RAM products. This was followed by HMOS-II, HMOS-III versions, and, eventually, a fully static CMOS version for battery-powered devices, manufactured using Intel's CHMOS processes. The original chip measured 33 mm² and minimum feature size was 3.2 ?m.

Application

, the microprocessor is provided with an instruction set which consists of various instructions such as MOV, ADD, SUB, JMP etc. These instructions are written in the form of a program which is used to perform various operations such as branching, addition, subtraction, bitwise logical and bit shift operations. More complex operations and other arithmetic operations must be implemented in software. For example, multiplication is implemented using a multiplication algorithm.

The 8085 processor has found marginal use in small scale computers up to the 21st century. The TRS-80 Model 100 line uses a 80C85. The CMOS version 80C85 of the NMOS/HMOS 8085 processor has/had several manufacturers, and some versions (eg. Tundra Semiconductor Corporation's CA80C85B) have additional functionality, eg. extra machine code instructions. One niche application for the rad-hard version of the 8085 has been in on-board instrument data processors for several NASA and ESA space physics missions.

REFERENCE-

http://www.howstuffworks.com/microprocessor.htm

http://www.webopedia.com/TERM/M/microprocessor.html

http://nptel.iitm.ac.in/courses/Webcourse-contents/IISc-BANG/Microprocessors%20and%20Microcontrollers/pdf/Lecture_Notes/LNm1.pdf

http://en.wikipedia.org/wiki/Microprocessor

http://www.cpu-world.com/CPUs/8086/