Many have pictured computer systems as having human or superhuman traits. Such views tend to exaggerate certain computer capabilities. The computer has also been described to be dumb machine since it is dependent entirely on those who control it. Use the wrong or faulty program, or use the wrong or inaccurate data, and you will get the wrong answer. The computer cannot think for itself. What is can do is extend man's problem-solving capabilities by performing many arithmetic, logic, branching and input/output instructions with lightning speed. It is powerful tool for extending man's brain power. It may be rightly called an intelligence amplifier.
Computers can enlarge man's brainpower because of the following capabilities and properties which had lead to the human or superhuman images created about it.
1. Ability to Perform Certain Logic Operations. Computers are symbol manipulators. It can manipulate in logical ways letter, numbers, words, sentences, mathematical expressions and other symbols to which people have giving meaning. It is able to perform a simple comparison and then, depending on the result, follow one of two or more predetermined branches or courses of action. This simple ability to compare is an important computer capability because more sophisticated questions can be answered by using combinations of comparison decisions.
2. Ability to Provide New Time Dimensions. The computer works one step at a time; it adds and subtracts numbers; it multiples and divides numbers; and it can be programmed to perform other mathematical operations. What is significant is the speed with which the computer can perform them. The computer is so fast that is saves a tremendous amount of time.
3. Ability to Store and Retrieve Information. The computer stores in internal storage both facts and instructions. The ease with which instructions can be changed gives the computer great flexibility . The access time required for information to be recalled from internal storage and be available for use is measured in microseconds or more precise units. Few machines that are used by man have this stored program ability.
4. Ability to control error. It has been estimated that a person would make one error in every 500- 1000 operations with a desk calculator. A computer can performed hundreds of thousands of arithmetic operations every second and can run error less for hours and days at a time.
5. Ability to Check Itself. Computers have the ability to check its own work. By a method known as parity checking, computers check on data when they enter storage, when they are moved internally, and when they leave in the form of output. The parity check performed by the computer involves the examination of each character's code to determine whether bits have been added or lost by mistake
Sunday, February 24, 2008
Monday, February 18, 2008
CLASSIFICATION OF COMPUTERS ACCORDING TO CAPACITY
The term "capacity" refers to the volume of work or the data processing capacity a computer can handle. Their performance is judged by the:
1. Amount of data that can be stored in memory
2. speed of internal operation of the computer
3. number and type of of peripheral devices
4. amount and type of software available for use with the computer
The capacity of early generation computers were determined by their physical size- the large the size, the greater the volume. In computer terms, size and speed of operation are at present proportionate to each other. Generally, though, recent, technology is tending to create smaller machines, making it possible to package equivalent speed and capacity in a smaller format.
1. Amount of data that can be stored in memory
2. speed of internal operation of the computer
3. number and type of of peripheral devices
4. amount and type of software available for use with the computer
The capacity of early generation computers were determined by their physical size- the large the size, the greater the volume. In computer terms, size and speed of operation are at present proportionate to each other. Generally, though, recent, technology is tending to create smaller machines, making it possible to package equivalent speed and capacity in a smaller format.
Computer System Classification
1. MICROCOMPUTERS= The mass production of silicon chips since 1971 has made it possible to put a "brain"into all sorts of machines. One such machine is the microcomputer. This machines has takes fullest advantage of the use of large-scale integration on silicon chips. The microprocessors literally contain a computer on a chip that can pass through the eye of needle. Microcomputers memories are generally made of semiconductors fabricated on silicons chips. It is a digital computer system under the control of a stored program that uses a microprocessor, a programmable read-only memory (ROM), and a random-access memory (RAM), The ROM defines the instructions to be executed by the computer while RAM is the functional equivalent of computer memory.
2. MINICOMPUTERS= Technological advances in the 1960's enabled manufactures to respond to the growing demand for a similar stand-alone machine, the minicomputer, to handle task that large computers could not perform economically. Minicomputer system (or small mainframe computers) provide faster operating speeds and larger storage capacities than microcomputers systems. They can support a large number of high-speed input/output devices. Several desk drives can be used to provide online access to large data files as required for direct- access processing.
Operating system developed for minicomputer systems generally support both multiprogramming and virtual storage. This means that many programs can be run concurrently. This type of computer system is very flexible and can be expanded to meet the needs of users.
Minicomputers usually have from 8k to 256K memory storage locations, and a relatively established applications software. although the minicomputer is not as powerful as the medium or large-size computer, it is quite close.
3. MEDIUM-SIZE COMPUTERS= it provide faster operating speeds and larger storage capabilities than small computer systems. They can support a large number of high-speed input-output devices, and several disk drives can be used to provide online access processing. Also support both multiprogramming and virtual storage. This allows the running of a variety of programs concurrently.
Medium-size computer system are very flexible; they can be expanded to meet the needs of users. The possibility of increasing the data processing capability of a computer by adding devices, such additional memory, and other peripheral devices, is called expandability.
4. LARGE COMPUTERS=are the ultimate in system sophistication, flexibility, and speed. They usually contain full control systems with minimal operator intervention. Large computer systems range from single-processing configurations to nationwide computer based networks involving general large computers. Large computers have storage capacities from 512K to 819K, and these computers have internal operating speeds measured in terms of nanoseconds, as a compared to smaller computers where speed in terms of microseconds.
5. SUPERCOMPUTERS= The biggest and fastest machines today are the supercomputers that are used when billions or even trillions of calculations are needed. These machines are essential for applications ranging from nuclear weapon to accurate weather forecasting.
Supercomputers are machines that have capabilities far beyond even the traditional large scale systems. Their speed is in the 100-million-instructions-per-second range.
2. MINICOMPUTERS= Technological advances in the 1960's enabled manufactures to respond to the growing demand for a similar stand-alone machine, the minicomputer, to handle task that large computers could not perform economically. Minicomputer system (or small mainframe computers) provide faster operating speeds and larger storage capacities than microcomputers systems. They can support a large number of high-speed input/output devices. Several desk drives can be used to provide online access to large data files as required for direct- access processing.
Operating system developed for minicomputer systems generally support both multiprogramming and virtual storage. This means that many programs can be run concurrently. This type of computer system is very flexible and can be expanded to meet the needs of users.
Minicomputers usually have from 8k to 256K memory storage locations, and a relatively established applications software. although the minicomputer is not as powerful as the medium or large-size computer, it is quite close.
3. MEDIUM-SIZE COMPUTERS= it provide faster operating speeds and larger storage capabilities than small computer systems. They can support a large number of high-speed input-output devices, and several disk drives can be used to provide online access processing. Also support both multiprogramming and virtual storage. This allows the running of a variety of programs concurrently.
Medium-size computer system are very flexible; they can be expanded to meet the needs of users. The possibility of increasing the data processing capability of a computer by adding devices, such additional memory, and other peripheral devices, is called expandability.
4. LARGE COMPUTERS=are the ultimate in system sophistication, flexibility, and speed. They usually contain full control systems with minimal operator intervention. Large computer systems range from single-processing configurations to nationwide computer based networks involving general large computers. Large computers have storage capacities from 512K to 819K, and these computers have internal operating speeds measured in terms of nanoseconds, as a compared to smaller computers where speed in terms of microseconds.
5. SUPERCOMPUTERS= The biggest and fastest machines today are the supercomputers that are used when billions or even trillions of calculations are needed. These machines are essential for applications ranging from nuclear weapon to accurate weather forecasting.
Supercomputers are machines that have capabilities far beyond even the traditional large scale systems. Their speed is in the 100-million-instructions-per-second range.
Wednesday, February 13, 2008
CLASSIFICATION BY TYPE OF DATA HANDLED
There are essentially two different types of computer processing. Each is made possible by a different kind of circuitry , and each is suitable for different purposes.
1. Analog Computers = The name analog comes from the word "analogous", meaning similar. Analog computers are used for scientific, engineering, and process control purposes. Because they deal with quantities that are continuously variable., they give only approximate results. This types of computer provides an analog or simulation of the object or system it represents. It is especially useful for solving problems that involve relationships between variable quantities in systems that change with time. The analog compute may express changing relationships in output in the form of graphs. It is able to create such pictures because it responds to changes in electrical voltages that match changes in variable quantities.
2. Digital Computers = Is a machine the specializes in counting. It operates by counting values that are discrete, or separate and distinct, unlike the continuous quantities that can be measured by the analog computer. Digital Computers are used for both business data processing and accuracy. The basic operation performed by a digital computer is addition. It can store the sums of addition problems as they accumulate, and can complete a single calculation in a fraction of a nanosecond. The digital computer is capable of storing data as long as needed, performing logical operations, editing input data, and printing out the results of its processing at hight speed.
3. Hybrid Computers= Although both analog and digital computers are extremely used in widely accepted in various industries, manufacturers have to attempted to designed a computer that combines the best features of both types. This special-purpose machine called a hybrid, computer, combines the measuring capabilities of the analog computer and the logical and control capabilities of the digital computer. It offers an efficient and economical method of working out special types of problems in science and various areas of engineering. Some Hybrid machines contain special equipment to convert analog voltages into digital voltages,and vice-versa.
1. Analog Computers = The name analog comes from the word "analogous", meaning similar. Analog computers are used for scientific, engineering, and process control purposes. Because they deal with quantities that are continuously variable., they give only approximate results. This types of computer provides an analog or simulation of the object or system it represents. It is especially useful for solving problems that involve relationships between variable quantities in systems that change with time. The analog compute may express changing relationships in output in the form of graphs. It is able to create such pictures because it responds to changes in electrical voltages that match changes in variable quantities.
2. Digital Computers = Is a machine the specializes in counting. It operates by counting values that are discrete, or separate and distinct, unlike the continuous quantities that can be measured by the analog computer. Digital Computers are used for both business data processing and accuracy. The basic operation performed by a digital computer is addition. It can store the sums of addition problems as they accumulate, and can complete a single calculation in a fraction of a nanosecond. The digital computer is capable of storing data as long as needed, performing logical operations, editing input data, and printing out the results of its processing at hight speed.
3. Hybrid Computers= Although both analog and digital computers are extremely used in widely accepted in various industries, manufacturers have to attempted to designed a computer that combines the best features of both types. This special-purpose machine called a hybrid, computer, combines the measuring capabilities of the analog computer and the logical and control capabilities of the digital computer. It offers an efficient and economical method of working out special types of problems in science and various areas of engineering. Some Hybrid machines contain special equipment to convert analog voltages into digital voltages,and vice-versa.
Monday, February 11, 2008
CLASSIFICATIONS OF COMPUTERS BY PURPOSE
Digital computers may be utilized for either special or general purposes.
1. General-Purpose Computers= This machines have the capability of dealing with variety of different problems, and are able to act in response to programs created to meet different needs. A general-purpose computer is one that has the ability to store different programs of instruction and thus to perform a variety of operations.
2. Special-Purpose Computers = as to the name implies, is designed to perform one specific tasks. The program of instructions is built into, or permanently stored in the machine. Specialization results in the given task being preformed very quickly and efficiently. Most special purpose computers have the capability of performing just one task. They are frequently referred to us "dedicated," because of their limitations to the specific task at hand.
1. General-Purpose Computers= This machines have the capability of dealing with variety of different problems, and are able to act in response to programs created to meet different needs. A general-purpose computer is one that has the ability to store different programs of instruction and thus to perform a variety of operations.
2. Special-Purpose Computers = as to the name implies, is designed to perform one specific tasks. The program of instructions is built into, or permanently stored in the machine. Specialization results in the given task being preformed very quickly and efficiently. Most special purpose computers have the capability of performing just one task. They are frequently referred to us "dedicated," because of their limitations to the specific task at hand.
CLASSIFICATIONS OF COMPUTERS
There is an almost bewildering variety of computers, and the number of models available is rapidly growing. To some extent this variety is redundant; many machines are similar in capacity. But to a greater extent the variety of computers is related to important differences in capacity and functions.
The distinctions among the various categories of computers has been subject to controversy. Computers may be classified according to their purpose, according to the kind of processing they do or types of data they use, and also according to the size of the machine and the speed of its internal operations.
Speed of operation is often the most important consideration in deciding which equipment to choose for a particular task. With today's machines, It is generally true that the bigger the machine, the faster the operating speed.
The distinctions among the various categories of computers has been subject to controversy. Computers may be classified according to their purpose, according to the kind of processing they do or types of data they use, and also according to the size of the machine and the speed of its internal operations.
Speed of operation is often the most important consideration in deciding which equipment to choose for a particular task. With today's machines, It is generally true that the bigger the machine, the faster the operating speed.
Monday, February 4, 2008
THE COMPUTER
As the name implies the word" Computer" comes from the term to compute, meaning to calculate. It is one word which is used frequently theses days, and it is common knowledge that the widespread use of computers is having a tremendous effect on all aspects of human life, both from individual and social point of view.
The computer's storage capacity, or memory, does not yet equal that of human brain, but computer capacity is rapidly increasing. In the future, it will undoubtedly exceed that of the human memory.
In General, A computer is an electronic system designed to manipulate data. They are machines for storing, moving, adding, and subtracting, and evaluation data. All Computers have four basic functions in common: input, processing, storage, and output. This is a true of all computers, from the largest general purpose main frame to the smallest personal computer.
Since computer are, after all, only machines, they have no initiative and cannot do any useful work until they have been properly prepared. This is done by providing them with sequences of instructions called a Program. These instructions control the manner in which the computer carries out its operational functions. Again a computer will perform only what it is told to do; it does not have the ability to evaluate information and take appropriate action on its own.
The computer's storage capacity, or memory, does not yet equal that of human brain, but computer capacity is rapidly increasing. In the future, it will undoubtedly exceed that of the human memory.
In General, A computer is an electronic system designed to manipulate data. They are machines for storing, moving, adding, and subtracting, and evaluation data. All Computers have four basic functions in common: input, processing, storage, and output. This is a true of all computers, from the largest general purpose main frame to the smallest personal computer.
Since computer are, after all, only machines, they have no initiative and cannot do any useful work until they have been properly prepared. This is done by providing them with sequences of instructions called a Program. These instructions control the manner in which the computer carries out its operational functions. Again a computer will perform only what it is told to do; it does not have the ability to evaluate information and take appropriate action on its own.
Sunday, February 3, 2008
STORED PROGRAM CONCEPTS
Before a computer can actually read data, process it, and produce information, it must read a set of instructions called a program, which actually indicate what processing is required. Programs, like data, are stored in the computer. This arrangement is referred to as the stored-program concept.
In the same manner, any calculating operation involves a number of steps that must be spelled out to the computer: reading, locating numbers in storage, performing the actual calculation, placing the result in storage, and writing out that result at the appropriate time. A calculation procedure, therefore is composed of a sequence of individual steps that leads to desired result. The steps are coded as instructions and read into the computer as part of a stored programs to direct processing.
It is a stored program that makes the computer" Automatic." Once the program is loaded and processing is initiated, the stored-program instructions are executed, one after another. No further human intervention is required.
A computer can solve a seemingly infinite variety of problems. To solve a particular problem, one has only to load a program designed to solve that type of problem into the internal storage unit of the computer. Any of the common input devices can be used to do this, because instructions.
The task of writing a series of instructions to direct the operations of a computer is called" Programming". The person who writes the instructions is called a "Programmer".
It is possible for more than one program to be stored in the computer at any given time. The only requirement is that sufficient storage locations are available for both the programs and necessary data. This is a termed multiprogramming.
Since only one instructions can be executed t a time, simultaneous execution of instructions from different programs is not possible. However, the computer can execute instructions from one program, then instructions from another program, then instructions from the the first program again, and so on. This type of processing is called concurrent processing.
In the same manner, any calculating operation involves a number of steps that must be spelled out to the computer: reading, locating numbers in storage, performing the actual calculation, placing the result in storage, and writing out that result at the appropriate time. A calculation procedure, therefore is composed of a sequence of individual steps that leads to desired result. The steps are coded as instructions and read into the computer as part of a stored programs to direct processing.
It is a stored program that makes the computer" Automatic." Once the program is loaded and processing is initiated, the stored-program instructions are executed, one after another. No further human intervention is required.
A computer can solve a seemingly infinite variety of problems. To solve a particular problem, one has only to load a program designed to solve that type of problem into the internal storage unit of the computer. Any of the common input devices can be used to do this, because instructions.
The task of writing a series of instructions to direct the operations of a computer is called" Programming". The person who writes the instructions is called a "Programmer".
It is possible for more than one program to be stored in the computer at any given time. The only requirement is that sufficient storage locations are available for both the programs and necessary data. This is a termed multiprogramming.
Since only one instructions can be executed t a time, simultaneous execution of instructions from different programs is not possible. However, the computer can execute instructions from one program, then instructions from another program, then instructions from the the first program again, and so on. This type of processing is called concurrent processing.
Friday, February 1, 2008
ADVANTAGES OF ELECTRONIC DATA PROCESSING
Electronic data processing systems are built to boost productivity and to improve the quality of work. They achieve these goals in several ways.
1. Speed = Since a computer is an electronic device, it operates as the speed of electric flow which is measured in billionths and trillionths of a second. It is faster than any other machine designed to do similar work. At such speeds, a computer can solve in less than a minute problems that would take at least ten hours on a punched card data processing system.
2. Accuracy= High speed processing by computers is accompanied by high-accuracy results. The electronic circuitry of computers is such that, when the machines are programmed correctly and when relatively assured. No other system can operate with as much accuracy as the electronic system.
A computer can be considered as 100% accurate. Checking circuits are built directly into the computer, so that computer errors that are undetected are extremely rare. Because of the speed and accuracy, computer systems are capable of processing large amounts of data more cheaply than if manual methods are used.
3. Automatic Operation = An electronic computer can carry out a sequence of many data processing operations without human intervention. The various operations are executed automatically by way of a stored computer program.
4.Decision Making capability= A computer can perform certain decision instructions automatically. Here a decision consist of two steps.
a. Determining whether a certain statement is true or false.
b. Based on the result, choosing one or the other course of action out of of alternatives included in the computer program.
5. Compact Storage= Electronic data processing systems have the ability to store large amounts of data in a compact ans easily retrievable form.
6. Discipline it Imposses= To solve a problem with a computer you must, first, understand the problem, and second, program the computer to give you the right answers. Understanding a problem is one thing, but understanding it to depth of detail and insight required to program the computer is a completely different matters.
1. Speed = Since a computer is an electronic device, it operates as the speed of electric flow which is measured in billionths and trillionths of a second. It is faster than any other machine designed to do similar work. At such speeds, a computer can solve in less than a minute problems that would take at least ten hours on a punched card data processing system.
2. Accuracy= High speed processing by computers is accompanied by high-accuracy results. The electronic circuitry of computers is such that, when the machines are programmed correctly and when relatively assured. No other system can operate with as much accuracy as the electronic system.
A computer can be considered as 100% accurate. Checking circuits are built directly into the computer, so that computer errors that are undetected are extremely rare. Because of the speed and accuracy, computer systems are capable of processing large amounts of data more cheaply than if manual methods are used.
3. Automatic Operation = An electronic computer can carry out a sequence of many data processing operations without human intervention. The various operations are executed automatically by way of a stored computer program.
4.Decision Making capability= A computer can perform certain decision instructions automatically. Here a decision consist of two steps.
a. Determining whether a certain statement is true or false.
b. Based on the result, choosing one or the other course of action out of of alternatives included in the computer program.
5. Compact Storage= Electronic data processing systems have the ability to store large amounts of data in a compact ans easily retrievable form.
6. Discipline it Imposses= To solve a problem with a computer you must, first, understand the problem, and second, program the computer to give you the right answers. Understanding a problem is one thing, but understanding it to depth of detail and insight required to program the computer is a completely different matters.
PEOPLEWARE
The term "peopleware" represents the personnel involved in systems analysis, programming, computer operations, system maintenance, and the like. Systems analysis and design are the jobs of the system analyst. Program development is the specialty of the programmer. System development is carried out by a computer operations, input data preparation staff, and output preparation clerks. Output preparation involves collating, bursting, and binding the reports before they are delivered to the user. Commonly, Analysts do some programming in addition to analysis.
Correspondingly, programmers do some systems work in addition to programming.
Correspondingly, programmers do some systems work in addition to programming.
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