erwin arnandy

8/6/2019 Erwin Arnandy

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Types of Computer

Analog computer

An analog computer does not operate with the digital signals. It recognizes data as a

continuous measurement of a physical property. It has no state .Analog computer is difficult

to operate and use. Its output is unusually displayed on a meter or graph Voltage, pressure,

Speed and Temperature and some physical properties that can be measured in this way.

Analog computer has low memory and fewer functions. It is usually built for special purpose.

Analog Computer is mainly used in the field of engineering and medical

An analog computer (spelt analogue in British English) is a form of computer that uses

continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to

model the problem being solved.

The Antikythera mechanism is believed to be the earliest known mechanical analog

computer. It was designed to calculate astronomical positions. It was discovered in

1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera

and Crete, and has been dated to circa 100 BC. Devices of a level of complexity

comparable to that of the Antikythera mechanism would not reappear until a

thousand years later.

The astrolabe was invented in the Hellenistic world in either the first or second

centuries BCE 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 sphericalastronomy.
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Muslim astronomers later produced many different types of astrolabes and used

them for over a thousand different problems related to astronomy, astrology,

horoscopes, navigation, surveying, timekeeping, Qibla (direction ofMecca), Salah

(prayer), etc.

Ab Rayhn al-Brn invented the first mechanical geared lunisolar calendar

astrolabe, an early fixed-wiredknowledge processing machinewith a gear train and

gear-wheels, circa 1000 AD.

The Planisphere was a star chartastrolabe also invented by Ab Rayhn al-Brnin

the early 11th century.

The Equatorium was an astrometic calculating instrument invented by Ab IshqIbrhm al-Zarql(Arzachel) in Islamic Spain circa 1015.

The "castle clock", anastronomical clockinvented by Al-Jazari in 1206, is considered

to be the first programmable analog computer. It displayed the zodiac, the solarand

lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing

automatic doors to open every hour, and five robotic musicians who play music when

struck by levers operated by a camshaft attached to a water wheel. The length ofday

and night could be re-programmed every day in order to account for the changing

lengths of day and night throughout the year.

An astrolabe incorporating a mechanical calendar computer and gear-wheels was

invented by Abi Bakr ofIsfahanin 1235.

A slide rule

The slide rule is a hand-operated analog computer for doing multiplication and

division, invented around 16201630, shortly after the publication of the concept of

the logarithm.

The differential analyser, a mechanical analog computer designed to solve

differential equations by integration, using wheel-and-disc mechanisms to perform
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the integration. Invented in 1876 by James Thomson (engineer), they were first built

in the 1920s and 1930s.

By 1912 Arthur Pollen had developed an electrically driven mechanical analog

computer forfire-control system, based on the differential analyser. It was used by

the Imperial Russian Navy in World War I.

World War II era gun directors and bomb sights used mechanical analog computers.

The Curta Calculatorwas a small cylindrical hand crank powered device which could

do multiplication, division, and a number of other operations.

The MONIAC Computerwas a hydraulic model of a national economy first unveiled

in 1949.

Computer Engineering Associates was spun out of Caltech in 1950 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.

Heathkit EC-1, an educational analog computer made by the Heath Company, USA

c. 1960.

Comdyna GP-6 analog computer introduced in 1968 and produced for 36 years.

Digital Computer

Some kinds of digital computer:

1. Supercomputer and Mainframe

Supercomputer is a broad term for one of

the fastest computers currently available.

Supercomputers are very expensive and are

employed for specialized applications that

require immense amounts of mathematical

calculations (number crunching). For example,

Image 1 : Super
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weather forecasting requires a supercomputer. Other uses of supercomputers scientific

simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research,

electronic design, and analysis of geological data (e.g. in petrochemical prospecting).

Perhaps the best known supercomputer manufacturer is Cray Research.

Mainframe was a term originally referring to the

cabinet containing the central processor unit or "main frame"

of a room-filling Stone Age batch machine. After the

emergence of smaller "minicomputer" designs in the early

1970s, the traditional big iron machines were described as

"mainframe computers" and eventually just as mainframes.

Nowadays a Mainframe is a very large and expensivecomputer capable of supporting hundreds, or even

thousands, of users simultaneously. The chief difference between a supercomputer and

a mainframe is that a supercomputer channels all its power into executing a few

programs as fast as possible, whereas a mainframe uses its power to execute many

programs concurrently. In some ways, mainframes are more powerful than

supercomputers because they support more simultaneous programs. But

supercomputers can execute a single program faster than a mainframe. The distinction

between small mainframes and minicomputers is vague, depending really on how the

manufacturer wants to market its machines.

Differences Mainframe from Supercomputer

A supercomputeris a computer that is at the frontline of current processing capacity,

particularly speed of calculation. Supercomputers are used for scientific and engineering

problems (high-performance computing) which are limited by processing speed and

memory size, while mainframes are used for problems which are limited by datamovement in input/output devices, reliability, and for handling multiple business

transactions concurrently. The differences are as follows:

Mainframes are measured in millions of instructions per second (MIPS) while

assuming typical instructions are integer operations, but supercomputers are

measured in floating pointoperations per second (FLOPS). Examples of integer

operations include moving data around in memory or checking values. Floating point

operations are mostly addition, subtraction, and multiplication with enough digits of

Image 2 :
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precision to model continuous phenomena such as weather prediction and nuclear

simulations. In terms of computational ability, supercomputers are more powerful.

Mainframes are built to be reliable for transaction processing as it is commonly

understood in the business world: a commercial exchange of goods, services, or

money. A typical transaction, as defined by the Transaction Processing Performance

Council, would include the updating to a database system for such things as

inventory control (goods), airline reservations (services), or banking (money). A

transaction could refer to a set of operations including disk read/writes, operating

system calls, or some form of data transfer from one subsystem to another. This

operation does not count toward the processing power of a computer. Transactionprocessing is not exclusive to mainframes but also used in the performance of

microprocessor-based servers and online networks.

2. Minicomputer

A minicomputer (colloquially, mini) is a

class of multi-usercomputers that lies in the

middle range of the computing spectrum, in

between the largest multi-user

systems (mainframe computers) and the

smallest single-user systems

(microcomputers orpersonal computers).

The class at one time formed a distinct group

with its own hardware and operating systems, but the contemporary term for this class of

system ismidrange computer, such as the higher-end SPARC, POWER and Itanium-

based systems from Sun Microsystems, IBM and Hewlett-Packard.

Several pioneering computer companies first built minicomputers, such

as DEC, Data General, and Hewlett-Packard (HP) (who now refers to

its HP3000 minicomputers as servers rather than minicomputers). And although

todays PCs and servers are clearly microcomputers physically, architecturally their

CPUs and operating systems have evolved largely by integrating features from

minicomputers.
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3. Workstation

It is a type of computer used for

engineering applications (CAD/CAM),

desktop publishing, software development,

and other types of applications that require a

moderate amount of computing power and

relatively high quality graphics capabilities.

Workstations generally come with a large, high-resolution graphics screen, at large

amount of RAM, built-in network support, and a graphical user interface. Most

workstations also have a mass storage device such as a disk drive, but a special type of

workstation, called a diskless workstation, comes without a disk drive. The most common

operating systems for workstations are UNIX and Windows NT. Like personal

computers, most workstations are single-user computers. However, workstations are

typically linked together to form a local-area network, although they can also be used as

stand-alone systems.

A significant segment of the desktop market are computers expected to perform

as workstations, but using PC operating systems and components. PC component

manufacturers will often segment their product line, and market premium components

which are functionally similar to the cheaper "consumer" models but feature a higher

level of robustness and/or performance. Notable examples of this are

the AMDOpteron, Intel Xeon processors, and the ATI FireGL and Nvidia

Quadro graphics processors.

A workstation class PC may have some of the following features:

support forECC memory

a larger number of memory sockets which use registered (buffered) modules

multiple processor sockets, powerful CPUs (for Intel CPU it will be server

derived Xeon instead of typical for PCs Core)

multiple displays

run reliable operating system with advanced features

high performance graphics card
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4. Personal computer

It can be defined as a small, relatively inexpensive

computer designed for an individual user. In price,

personal computers range anywhere from a few hundred

pounds to over five thousand pounds. All are based on

the microprocessor technology that enables

manufacturers to put an entire CPU on one chip.

Businesses use personal computers for word processing, accounting, desktop

publishing, and for running spreadsheet and database management applications. At

home, the most popular use for personal computers is for playing games and recently for

surfing the Internet.

Personal computers first appeared in the late 1970s. One of the first and most

popular personal computers was the Apple II, introduced in 1977 by Apple Computer.

During the late 1970s and early 1980s, new models and competing operating systems

seemed to appear daily. Then, in 1981, IBM entered the fray with its first personal

computer, known as the IBM PC. The IBM PC quickly became the personal computer of

choice, and most other personal computer manufacturers fell by the wayside. P.C. is

short for personal computer or IBM PC.

One of the few companies to survive IBM's onslaught was Apple Computer, which

remains a major player in the personal computer marketplace. Other companies

adjusted to IBM's dominance by building IBM clones, computers that were internally

almost the same as the IBM PC, but that cost less. Because IBM clones used the same

microprocessors as IBM PCs, they were capable of running the same software. Over the

years, IBM has lost much of its influence in directing the evolution of PCs. Therefore

after the release of the first PC by IBM the term PC increasingly came to mean IBM or

IBM-compatible personal computers, to the exclusion of other types of personal

computers, such as Macintoshes. In recent years, the term PC has become more and

more difficult to pin down. In general, though, it applies to any personal computer based

on an Intel microprocessor, or on an Intel-compatible microprocessor. For nearly every

other component, including the operating system, there are several options, all of which

fall under the rubric of PC


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Today, the world of personal computers is basically divided between Apple

Macintoshes and PCs. The principal characteristics of personal computers are that they

are single-user systems and are based on microprocessors. However, although personal

computers are designed as single-user systems, it is common to link them together to

form a network. In terms of power, there is great variety. At the high end, the distinction

between personal computers and workstations has faded. High-end models of the

Macintosh and PC offer the same computing power and graphics capability as low-end

workstations by Sun Microsystems, Hewlett-Packard, and DEC

5. Tower model

The term refers to a computer in which the power supply,

motherboard, and mass storage devices are stacked on top ofeach other in a cabinet. This is in contrast to desktop models, in

which these components are housed in a more compact box.

The main advantage of tower models is that there are fewer

space constraints, which makes installation of additional storage devices easier.

6. Notebook computer

An extremely lightweight personal computer.

Notebook computers typically weigh less than 6 pounds

and are small enough to fit easily in a briefcase. Aside from

size, the principal difference between a notebook computer

and a personal computer is the display screen. Notebook

computers use a variety of techniques, known as flat-panel

technologies, to produce a lightweight and non-bulky

display screen. The quality of notebook display screens varies considerably. In terms of

computing power, modern notebook computers are nearly equivalent to personal

computers. They have the same CPUs, memory capacity, and disk drives. However, all

this power in a small package is expensive. Notebook computers cost about twice as

much as equivalent regular-sized computers. Notebook computers come with battery

packs that enable you to run them without plugging them in. However, the batteries need

to be recharged every few hours

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7. Netbook

Netbooks are a category of small,

lightweight, legacy-free, and inexpensive laptop

computers. At their inception in late 2007 as smaller

notebooks optimized for low weight and low cost

netbooks omitted certain features (e.g., the optical

drive), featured smaller screens and keyboards, and

offered reduced computing power when compared to a full-sized laptop. Over the

course of their evolution, netbooks have ranged in size from below 5" screen

diagonal to 12". A typical weight is 1 kg (23 pounds). Often significantly less

expensive than otherlaptops, by mid-2009, some wireless data carriers began to

offer netbooks to users "free of charge", with an extended service contract purchase

Netbooks typically have less powerful hardware than larger laptop computers.

Some netbooks do not even have a conventional hard drive. Such netbooks

use solid-state storage devices instead, as these require less power, are faster,

lighter, and generally more shock-resistant, but with much less storage capacity

(such as 32, 64, or 128 GB compared to the 100 GB to 2 TB mechanical hard drives

typical of many notebooks/laptop computers).

All netbooks on the market today support Wi-Fi wireless networking and many

can be used on mobile telephone networks with data capability (for example, 3G).

Mobile data plans are supplied under contract in the same way as mobile telephones.

Some also includeethernet and/ormodem ports, forbroadband ordial-up Internet

access, respectively.

Netbooks are a growing trend in education for several reasons. The need to

prepare children for 21st century lifestyles, combined with hundreds of new

educational tools that can be found online, and a growing emphasis on student

centered learning are three of the biggest contributing factors to the rising use of

Netbook technology in schools. Dell was one of the first to mass produce a

ruggedised netbook for the education sector, by having a rubber outlay, touchscreen

and network activity light to show the teacher the netbook is online.

Netbooks offer several distinct advantages in educational settings. First, their

compact size and weight make for an easy fit in student work areas. Similarly, the

small size make Netbooks easier to transport than heavier, larger sized traditional

laptops. In addition, prices ranging from $200$600 dollars mean the affordability of

Netbooks can be a relief to school budget makers.

8. Hand-held computer
http://en.wikipedia.org/wiki/Legacy-free_PChttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Optical_drivehttp://en.wikipedia.org/wiki/Optical_drivehttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Hard_disk_drivehttp://en.wikipedia.org/wiki/Solid-state_drivehttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Wireless_networkinghttp://en.wikipedia.org/wiki/Mobile_networkhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/Ethernet_over_twisted_pairhttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Dial-up_Internet_accesshttp://en.wikipedia.org/wiki/Dial-up_Internet_accesshttp://en.wikipedia.org/wiki/Legacy-free_PChttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Optical_drivehttp://en.wikipedia.org/wiki/Optical_drivehttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Hard_disk_drivehttp://en.wikipedia.org/wiki/Solid-state_drivehttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Wireless_networkinghttp://en.wikipedia.org/wiki/Mobile_networkhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/Ethernet_over_twisted_pairhttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Dial-up_Internet_accesshttp://en.wikipedia.org/wiki/Dial-up_Internet_access


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A portable computer that is small enough to be

held in ones hand. Although extremely convenient to

carry, handheld computers have not replaced notebook

computers because of their small keyboards and

screens. The most popular hand-held computers are

those that are specifically designed to provide PIM

(personal information manager) functions, such as a

calendar and address book. Some manufacturers are trying to solve the small keyboard

problem by replacing the keyboard with an electronic pen. However, these pen-based

devices rely on handwriting recognition technologies, which are still in their infancy.

Hand-held computers are also called PDAs, palmtops and pocket computers.

9. PDA

Short for personal digital assistant, a handheld device that combines

computing, telephone/fax, and networking features. A typical PDA can function as a

cellular phone, fax sender, and personal organizer. Unlike portable computers, most

PDAs are pen-based, using a stylus rather than a keyboard for input. This means that

they also incorporate handwriting recognition features. Some PDAs can also react to

voice input by using voice recognition technologies. The field of PDA was pioneered by

Apple Computer, which introduced the Newton MessagePad in 1993. Shortly thereafter,

several other manufacturers offered similar products. To date, PDAs have had only

modest success in the marketplace, due to their high price tags and limited applications.

However, many experts believe that PDAs will eventually become common gadgets.

PDAs are also called palmtops, hand-held computers

and pocket computers.


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10. Wearable Computer

Wearable computers are digital devices that are worn on the body. This type

ofwearable technology has been used in behavioral modeling, health monitoring

systems, information technologies and media development. Wearable computers areespecially useful for applications that require computational support while the user's

hands, voice, eyes, arms or attention are actively engaged with the physical

environment.

"Wearable computing" is an active

topic of research, with areas of study

including user

interface design, augmented

reality, pattern recognition, use of wearables for specific applications

ordisabilities, electronic

textiles and fashion design. Many issues

are common to the wearables, mobile computing, ambient intelligence and ubiquitous

computing researchcommunities, including power management and heat dissipation,

software architectures, wireless and personal area networks.

One of the main features of a wearable computer is consistency. There is a

constant interaction between the computer and user, i.e. there is no need to turn thedevice on or off. Another feature is the ability to multi-task. It is not necessary to stop

what you are doing to use the device; it is augmented into all other actions. These

devices can be incorporated by the user to act like a prosthetic. It can therefore be an

extension of the users mind and/or body.

Evidence of the allure of the wearable computer and the weak market acceptance is

evident with market leading PanasonicComputer Solutions Company's failed product in

this market. Panasonic has specialized in mobile computing with theirToughbook line for

over 10 years and has extensive market research into the field of portable, wearable

computing products. In 2002, Panasonic introduced a wearable brick computercoupled

with a handheld or armworn touchscreen. The brick would communicate wirelessly to the

screen, and concurrently the brick would communicate wirelessly out to the internet or

other networks. The wearable brick was quietly pulled from the market in 2005, while the

screen evolved to a thin client touchscreen used with a handstrap.

11. Server
http://en.wikipedia.org/wiki/Wearable_technologyhttp://en.wikipedia.org/wiki/Behavioral_modelinghttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/Augmented_realityhttp://en.wikipedia.org/wiki/Augmented_realityhttp://en.wikipedia.org/wiki/Pattern_recognitionhttp://en.wikipedia.org/wiki/Disabilitieshttp://en.wikipedia.org/wiki/Electronic_textilehttp://en.wikipedia.org/wiki/Electronic_textilehttp://en.wikipedia.org/wiki/Fashion_designhttp://en.wikipedia.org/wiki/Mobile_computinghttp://en.wikipedia.org/wiki/Ambient_intelligencehttp://en.wikipedia.org/wiki/Ubiquitous_computinghttp://en.wikipedia.org/wiki/Ubiquitous_computinghttp://en.wikipedia.org/wiki/Scientific_communityhttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Personal_area_networkhttp://en.wikipedia.org/wiki/Interactionhttp://en.wikipedia.org/wiki/Prosthetichttp://en.wikipedia.org/wiki/Panasonichttp://en.wikipedia.org/wiki/Toughbookhttp://en.wikipedia.org/w/index.php?title=Brick_computer&action=edit&redlink=1http://en.wikipedia.org/wiki/Thin_clienthttp://en.wikipedia.org/wiki/Wearable_technologyhttp://en.wikipedia.org/wiki/Behavioral_modelinghttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/Augmented_realityhttp://en.wikipedia.org/wiki/Augmented_realityhttp://en.wikipedia.org/wiki/Pattern_recognitionhttp://en.wikipedia.org/wiki/Disabilitieshttp://en.wikipedia.org/wiki/Electronic_textilehttp://en.wikipedia.org/wiki/Electronic_textilehttp://en.wikipedia.org/wiki/Fashion_designhttp://en.wikipedia.org/wiki/Mobile_computinghttp://en.wikipedia.org/wiki/Ambient_intelligencehttp://en.wikipedia.org/wiki/Ubiquitous_computinghttp://en.wikipedia.org/wiki/Ubiquitous_computinghttp://en.wikipedia.org/wiki/Scientific_communityhttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Personal_area_networkhttp://en.wikipedia.org/wiki/Interactionhttp://en.wikipedia.org/wiki/Prosthetichttp://en.wikipedia.org/wiki/Panasonichttp://en.wikipedia.org/wiki/Toughbookhttp://en.wikipedia.org/w/index.php?title=Brick_computer&action=edit&redlink=1http://en.wikipedia.org/wiki/Thin_client


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In computing, the term serveris used to refer to one of the following:

a computer program running to serve the needs or requests of other programs

(referred to in this context as "clients") which may or may not be running on the same

computer.

a physical computer dedicated to running one or more such services, to serve the

needs of programs running on other computers on the same network.

a software/hardware system (i.e. a software service running on a dedicated

computer) such as a database server, file server, mail server, orprint server.

In computer networking, a serveris a program that operates as

a socket listener. The term serveris also often generalized to describe ahost that is

deployed to execute one or more such programs.

A server computeris a computer, or series of computers,

that link other computers or electronic devices together. They often

provide essential services across a network, either to private users

inside a large organization or to public users via the internet. For

example, when you enter a query in a search engine, the query is

sent from your computer over the internet to the servers that store

all the relevant web pages. The results are sent back by the server

to your computer.

Many servers have dedicated functionality such as web servers, print servers,

and database servers. Enterprise servers are servers that are used in a business

context.

Server-oriented operating systems tend to have certain features in common that

make them more suitable for the server environment, such as:

GUI not available or optional

ability to reconfigure and update both hardware and software to some extent without

restart,

advanced backup facilities to permit regular and frequent online backups of

critical data,

transparent data transfer between different volumes or devices,

flexible and advanced networking capabilities,

automation capabilities such as daemons in UNIX and services in Windows, and

tight system security, with advanced user, resource, data, and memory protection.
http://en.wikipedia.org/wiki/Client_(computing)http://en.wikipedia.org/wiki/Database_serverhttp://en.wikipedia.org/wiki/File_serverhttp://en.wikipedia.org/wiki/Mail_serverhttp://en.wikipedia.org/wiki/Print_serverhttp://en.wikipedia.org/wiki/Internet_sockethttp://en.wikipedia.org/wiki/Host_(network)http://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Web_servershttp://en.wikipedia.org/wiki/Print_serverhttp://en.wikipedia.org/wiki/Database_servershttp://en.wikipedia.org/wiki/GUIhttp://en.wikipedia.org/wiki/Reconfigurable_computinghttp://en.wikipedia.org/wiki/Backuphttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Transparency_(computing)http://en.wikipedia.org/wiki/Volume_(computing)http://en.wikipedia.org/wiki/Daemon_(computer_software)http://en.wikipedia.org/wiki/Windows_servicehttp://en.wikipedia.org/wiki/Client_(computing)http://en.wikipedia.org/wiki/Database_serverhttp://en.wikipedia.org/wiki/File_serverhttp://en.wikipedia.org/wiki/Mail_serverhttp://en.wikipedia.org/wiki/Print_serverhttp://en.wikipedia.org/wiki/Internet_sockethttp://en.wikipedia.org/wiki/Host_(network)http://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Web_servershttp://en.wikipedia.org/wiki/Print_serverhttp://en.wikipedia.org/wiki/Database_servershttp://en.wikipedia.org/wiki/GUIhttp://en.wikipedia.org/wiki/Reconfigurable_computinghttp://en.wikipedia.org/wiki/Backuphttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Transparency_(computing)http://en.wikipedia.org/wiki/Volume_(computing)http://en.wikipedia.org/wiki/Daemon_(computer_software)http://en.wikipedia.org/wiki/Windows_service


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Hybrid computer

Hybrid computers are computers that exhibit features of analog computers and digital

computers. The digital component normally serves as the controller and provides logicaloperations, while the analog component normally serves as a solver ofdifferential equations.

Polish Hybrid computerWAT 1001

In general, analog computers are extraordinarily fast, since they can solve most complex

equations at the rate at which a signal traverses the circuit, which is generally anappreciable fraction of the speed of light. On the other hand, the precision of analog

computers is not good; they are limited to three, or at most, four digits of precision.

Digital computers can be built to take the solution of equations to almost unlimited precision,

but quite slowly compared to analog computers. Generally, complex equations are

approximated using iterative numerical methods which take huge numbers of iterations,

depending on how good the initial "guess" at the final value is and how much precision is

desired. (This initial guess is known as the numerical seed for the iterative process.) Formany real-time operations, the speed of such digital calculations is too slow to be of much

use (e.g., for very high frequency phased array radars or for weather calculations), but the

precision of an analog computer is insufficient.
http://en.wikipedia.org/wiki/Analog_computerhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Logical_operationhttp://en.wikipedia.org/wiki/Logical_operationhttp://en.wikipedia.org/wiki/Differential_equationshttp://en.wikipedia.org/w/index.php?title=WAT_1001&action=edit&redlink=1http://en.wikipedia.org/wiki/Analog_computershttp://en.wikipedia.org/wiki/Precisionhttp://en.wikipedia.org/wiki/Digital_computershttp://en.wikipedia.org/wiki/Iterativehttp://en.wikipedia.org/wiki/Numerical_methodhttp://en.wikipedia.org/wiki/Real-time_computinghttp://en.wikipedia.org/wiki/File:WAT_1001.jpghttp://en.wikipedia.org/wiki/Analog_computerhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Logical_operationhttp://en.wikipedia.org/wiki/Logical_operationhttp://en.wikipedia.org/wiki/Differential_equationshttp://en.wikipedia.org/w/index.php?title=WAT_1001&action=edit&redlink=1http://en.wikipedia.org/wiki/Analog_computershttp://en.wikipedia.org/wiki/Precisionhttp://en.wikipedia.org/wiki/Digital_computershttp://en.wikipedia.org/wiki/Iterativehttp://en.wikipedia.org/wiki/Numerical_methodhttp://en.wikipedia.org/wiki/Real-time_computing


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Hybrid computers can be used to obtain a very good but relatively imprecise 'seed'

value, using an analog computer front-end, which is then fed into a digital computer iterative

process to achieve the final desired degree of precision. With a three or four digit, highly

accurate numerical seed, the total digital computation time necessary to reach the desired

precision is dramatically reduced, since many fewer iterations are required.

Consider that the nervous system in animals is a form of hybrid computer. Signals pass

across the synapses from one nerve cell to the next as discrete (digital) packets of

chemicals, which are then summed within the nerve cell in an analog fashion by building an

electro-chemical potential until its threshold is reached, whereupon it discharges and sends

out a series of digital packets to the next nerve cell. The advantages are at least threefold:

noise within the system is minimized (and tends not to be additive), no common grounding

system is required, and there is minimal degradation of the signal even if there are

substantial differences in activity of the cells along a path (only the signal delays tend tovary). The individual nerve cells are analogous to analog computers; the synapses are

analogous to digital computers.
http://en.wikipedia.org/wiki/Precisehttp://en.wikipedia.org/wiki/Significant_figureshttp://en.wikipedia.org/wiki/Significant_figureshttp://en.wikipedia.org/wiki/Nervous_systemhttp://en.wikipedia.org/wiki/Synapseshttp://en.wikipedia.org/wiki/Nerve_cellhttp://en.wikipedia.org/wiki/Thresholdhttp://en.wikipedia.org/wiki/Precisehttp://en.wikipedia.org/wiki/Significant_figureshttp://en.wikipedia.org/wiki/Significant_figureshttp://en.wikipedia.org/wiki/Nervous_systemhttp://en.wikipedia.org/wiki/Synapseshttp://en.wikipedia.org/wiki/Nerve_cellhttp://en.wikipedia.org/wiki/Threshold

erwin arnandy

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