Units space devices of computer complexes and analog and analog-digital machines
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An analog computer or analogue computer is a type of computer that uses the continuously changeable aspects of physical phenomena such as electrical , mechanical , or hydraulic quantities to model the problem being solved. In contrast, digital computers represent varying quantities symbolically and by discrete values of both time and amplitude.
Analog computers can have a very wide range of complexity. Analog computers were widely used in scientific and industrial applications even after the advent of digital computers, because at the time they were typically much faster, but they started to become obsolete as early as the s and s, although remained in use in some specific applications, such as aircraft flight simulators , the flight computer in aircraft , and for teaching control systems in universities.
More complex applications, such as aircraft flight simulators and synthetic aperture radar , remained the domain of analog computing and hybrid computing well into the s, since digital computers were insufficient for the task. This is a list of examples of early computation devices which are considered to be precursors of the modern computers.
Some of them may even have been dubbed as 'computers' by the press, although they may fail to fit the modern definitions. The Antikythera mechanism was an orrery and is believed to be an early mechanical analog computer, according to Derek J.
It was discovered in in the Antikythera wreck off the Greek island of Antikythera , between Kythera and Crete , and has been dated to circa BC during the Hellenistic period of Greece. Devices of a level of complexity comparable to that of the Antikythera mechanism would not reappear until a thousand years later. Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use.
The planisphere was first described by Ptolemy in the 2nd century AD. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BC and is often attributed to Hipparchus. A combination of the planisphere and dioptra , the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy.
An astrolabe incorporating a mechanical calendar computer   and gear -wheels was invented by Abi Bakr of Isfahan , Persia in The castle clock , a hydropowered mechanical astronomical clock invented by Al-Jazari in , was the first programmable analog computer. The sector , a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation.
The planimeter was a manual instrument to calculate the area of a closed figure by tracing over it with a mechanical linkage. The slide rule was invented around —, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions.
Aviation is one of the few fields where slide rules are still in widespread use, particularly for solving time—distance problems in light aircraft. The tide-predicting machine invented by Sir William Thomson in was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location. The differential analyser , a mechanical analog computer designed to solve differential equations by integration , used wheel-and-disc mechanisms to perform the integration.
In James Thomson had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of the ball-and-disk integrators. The torque amplifier was the advance that allowed these machines to work. Starting in the s, Vannevar Bush and others developed mechanical differential analyzers. It was an analog computer which related vital variables of the fire control problem to the movement of one's own ship and that of a target ship.
It was often used with other devices, such as a Vickers range clock to generate range and deflection data so the gun sights of the ship could be continuously set. A number of versions of the Dumaresq were produced of increasing complexity as development proceeded. By Arthur Pollen had developed an electrically driven mechanical analog computer for fire-control systems , based on the differential analyser.
Starting in , AC network analyzers were constructed to solve calculation problems related to electrical power systems that were too large to solve with numerical methods at the time. Since network analyzers could handle problems too large for analytic methods or hand computation, they were also used to solve problems in nuclear physics and in the design of structures. More than 50 large network analyzers were built by the end of the s. World War II era gun directors , gun data computers , and bomb sights used mechanical analog computers.
In the period — in the Netherlands Johan van Veen developed an analogue computer to calculate and predict tidal currents when the geometry of the channels are changed.
Around this idea was developed into the Deltar , an analogue computer supporting the closure of estuaries in the southwest of the Netherlands the Delta Works. It consisted of over electron tubes and used dials and plug-in connectors to program. Computer Engineering Associates was spun out of Caltech in to provide commercial services using the "Direct Analogy Electric Analog Computer" "the largest and most impressive general-purpose analyzer facility for the solution of field problems" developed there by Gilbert D.
McCann, Charles H. Wilts, and Bart Locanthi. Educational analog computers illustrated the principles of analog calculation. The relative resistance of the potentiometer was then equivalent to the formula of the equation being solved. Multiplication or division could be performed depending on which dials were considered inputs and which was the output. Accuracy and resolution was limited and a simple slide rule was more accurate; however, the unit did demonstrate the basic principle. Analog computer designs were published in electronics magazines.
Another more modern hybrid computer design was published in Everyday Practical Electronics in In industrial process control , analog loop controllers were used to automatically regulate temperature, flow, pressure, or other process conditions. The technology of these controllers ranged from purely mechanical integrators, through vacuum-tube and solid-state devices, to emulation of analog controllers by microprocessors.
The similarity between linear mechanical components, such as springs and dashpots viscous-fluid dampers , and electrical components, such as capacitors , inductors , and resistors is striking in terms of mathematics. They can be modeled using equations of the same form. However, the difference between these systems is what makes analog computing useful.
If one considers a simple mass—spring system, constructing the physical system would require making or modifying the springs and masses. This would be followed by attaching them to each other and an appropriate anchor, collecting test equipment with the appropriate input range, and finally, taking measurements. In more complicated cases, such as suspensions for racing cars, experimental construction, modification, and testing is both complicated and expensive.
The electrical equivalent can be constructed with a few operational amplifiers op amps and some passive linear components; all measurements can be taken directly with an oscilloscope.
In the circuit, the simulated 'stiffness of the spring', for instance, can be changed by adjusting the parameters of a capacitor. The electrical system is an analogy to the physical system, hence the name, but it is less expensive to construct, generally safer, and typically much easier to modify.
As well, an electronic circuit can typically operate at higher frequencies than the system being simulated. This allows the simulation to run faster than real time which could, in some instances, be hours, weeks, or longer.
Experienced users of electronic analog computers said that they offered a comparatively intimate control and understanding of the problem, relative to digital simulations. The drawback of the mechanical-electrical analogy is that electronics are limited by the range over which the variables may vary due to the fixed supply voltage. Therefore each problem has to be scaled to its parameters and dimensions, e.
Improperly scaled problems might suffer from higher noise levels. Floating-point digital calculations have a huge dynamic range but might also suffer from imprecision if tiny differences of huge values lead to numerical instability.
These electric circuits can also easily perform a wide variety of simulations. For example, voltage can simulate water pressure and electric current can simulate rate of flow in terms of cubic metres per second. An integrator can provide the total accumulated volume of liquid, using an input current proportional to the possibly varying flow rate. Analog computers are especially well-suited to representing situations described by differential equations.
Occasionally, they were used when a system of differential equations proved very difficult to solve by traditional means. The circuit has to consider that both integration and addition units invert the signal polarity.
The accuracy of an analog computer is limited by its computing elements as well as quality of the internal power and electrical interconnections. The precision of the analog computer readout was limited chiefly by the precision of the readout equipment used, generally three or four significant figures. The precision of a digital computer is limited by the word size; arbitrary-precision arithmetic , while relatively slow, provides any practical degree of precision that might be needed.
However, in most cases the precision of an analog computer is absolutely sufficient given the uncertainty of the model characteristics and its technical parameters. Many small computers dedicated to specific computations are still part of industrial regulation equipment, but from the s to the s, general-purpose analog computers were the only systems fast enough for real time simulation of dynamic systems, especially in the aircraft, military and aerospace field.
In the s, the major manufacturer was Electronic Associates of Princeton, New Jersey , with its R Analog Computer vacuum tubes, 20 integrators and subsequently its EAI Analog Computer solid state operational amplifiers, 64 integrators. Although the basic technology for analog computers is usually operational amplifiers also called "continuous current amplifiers" because they have no low frequency limitation , in the s an attempt was made in the French ANALAC computer to use an alternative technology: medium frequency carrier and non dissipative reversible circuits.
In the s every big company and administration concerned with problems in dynamics had a big analog computing center, for example:. Analog computing devices are fast, digital computing devices are more versatile and accurate, so the idea is to combine the two processes for the best efficiency. An example of such hybrid elementary device is the hybrid multiplier where one input is an analog signal, the other input is a digital signal and the output is analog.
It acts as an analog potentiometer upgradable digitally. This kind of hybrid technique is mainly used for fast dedicated real time computation when computing time is very critical as signal processing for radars and generally for controllers in embedded systems. In the early s analog computer manufacturers tried to tie together their analog computer with a digital computer to get the advantages of the two techniques.
In such systems, the digital computer controlled the analog computer, providing initial set-up, initiating multiple analog runs, and automatically feeding and collecting data. The digital computer may also participate to the calculation itself using analog-to-digital and digital-to-analog converters.
The largest manufacturer of hybrid computers was Electronics Associates. Their hybrid computer model was made of a digital computer and one or more analog consoles. These systems were mainly dedicated to large projects such as the Apollo program and Space Shuttle at NASA, or Ariane in Europe, especially during the integration step where at the beginning everything is simulated, and progressively real components replace their simulated part.
Only one company was known as offering general commercial computing services on its hybrid computers, CISI of France, in the s. The best reference in this field is the , simulations runs for each certification of the automatic landing systems of Airbus and Concorde aircraft. After , purely digital computers progressed more and more rapidly and were fast enough to compete with analog computers.
One key to the speed of analog computers was their fully parallel computation, but this was also a limitation.
The more equations required for a problem, the more analog components were needed, even when the problem wasn't time critical. Today there are no more big hybrid computers, but only hybrid components. While a wide variety of mechanisms have been developed throughout history, some stand out because of their theoretical importance, or because they were manufactured in significant quantities. Most practical mechanical analog computers of any significant complexity used rotating shafts to carry variables from one mechanism to another.
Cables and pulleys were used in a Fourier synthesizer, a tide-predicting machine , which summed the individual harmonic components.
Data Management for the Humanities
An analog computer or analogue computer is a type of computer that uses the continuously changeable aspects of physical phenomena such as electrical , mechanical , or hydraulic quantities to model the problem being solved. In contrast, digital computers represent varying quantities symbolically and by discrete values of both time and amplitude. Analog computers can have a very wide range of complexity.
Speed of work. Advantages include the huge potential savings and greater scalability of systems. Instead of them concentrating on the patient's needs, the doctors and nurses or MA's are busy putting all that information in the computer. Advantages of Integrate Circuit or IC It is quite small in size practically around 20, electronic components can be incorporated in a single square inch of IC chip. First, It is important to clarify that both are digital audio files, and the main difference is the way they produce sound.
Advantages And Disadvantages Of Analog Digital And Hybrid Computers
A computer is a machine for manipulating data according to a list of instructions. Computers take numerous physical forms. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers. Today, computers can be made small enough to fit into a wrist watch and be powered from a watch battery. Society has come to recognize personal computers and their portable equivalent, the laptop computer, as icons of the information age; they are what most people think of as "a computer. Embedded computers are small, simple devices that are often used to control other devices—for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys. The ability to store and execute programs makes computers extremely versatile and distinguishes them from calculators.
Uses Of Digital Computer
Digital Computer. The basic principle of his calculator is still used today in water meters and modern-day odometers. Compare analog computer. Fifth Generation -till date : Super computer The characteristics of computers that have made them so powerful and universally useful are speed, accuracy, diligence, versatility and storage capacity.
Although analog computation was eclipsed by digital computation in the second half of the twentieth century, it is returning as an importantalternative computing technology. Indeed, as explained in this article, theoretical results imply that analog computation can escape from the limitationsof digital computation. Furthermore, analog computation has emerged as an important theoretical framework for discussing computation in the brain andother natural systems. Analog computation gets its name from an analogy , orsystematic relationship, between the physical processes in the computer and those in thesystem it is intended to model or simulate the primarysystem.
History of Computers
We humans are biological animals. We have evolved over millions of years to function well in the environment, to survive. We are analog devices following biological modes of operation.SEE VIDEO BY TOPIC: Analog vs Digital Control Signals: The Basics
Ask a Librarian. There are a number of competing terms used to describe the activity of managing digital materials for research: digital curation, digital stewardship, data curation, digital archiving. As a simple definition, data curation is "the active and ongoing management of data throughout its entire lifecycle of interest and usefulness to scholarship. This checklist, from the UK Data Archive, can help you identify what to put in place for good data practices, and which actions to take to optimize data sharing. The mission of the UCLA Library is to provide access to and delivery of information resources to UCLA students, faculty, and staff in support of the research and instructional mission of the university. Relying on its highly skilled staff, the Library encourages innovation, capitalizes on appropriate technologies, forges effective partnerships and aggressively promotes excellence.
We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog—digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA—protein computation in cells.
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Hybrid Computer Pdf
Last updated: December 25, I t was probably the worst prediction in history. Back in the s, Thomas Watson, boss of the giant IBM Corporation, reputedly forecast that the world would need no more than "about five computers. To be fair to Watson, computers have changed enormously in that time.
Analog synthetic biology
We have heard a lot about digital computers, but, analog computers are rarely mentioned. We come across so many analog computers, but we hardly notice them as a computer. The basic difference between analog and digital computers is the type of data they process.
Digital Signal: A digital signal is a signal that represents data as a sequence of discrete values; at any given time it can only take on one of a finite number of values. Analog Signal: An analog signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity i. The most common technique to change an analog signal to digital data is called pulse code modulation PCM. A PCM encoder has the following three processes:.
In fact, calculation underlies many activities that are not normally thought of as mathematical. Walking across a room, for instance, requires many complex, albeit subconscious, calculations. Computers, too, have proved capable of solving a vast array of problems, from balancing a checkbook to even—in the form of guidance systems for robots—walking across a room. Before the true power of computing could be realized, therefore, the naive view of calculation had to be overcome. The inventors who laboured to bring the computer into the world had to learn that the thing they were inventing was not just a number cruncher, not merely a calculator. For example, they had to learn that it was not necessary to invent a new computer for every new calculation and that a computer could be designed to solve numerous problems, even problems not yet imagined when the computer was built. They also had to learn how to tell such a general problem-solving computer what problem to solve.
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