In recent years, the computer industry has grow at a phenomenal pace. In a short time of 35 years or so computers have improved tremendously. In the last decade the speed of computer has increase. The cast per unit of calculating has gone down by 500 times. The storage capacity is increasing so fast that now it seems that nothing is impossible to store. Large data can be stored in very small devices.
First Generation of computer(1942-1955):-
Until 1951, electronic computers were exclusive possession of scientists and the military. Till then nobody tried to use them for business purpose. The idea of marketing them was conceived mushily and Eckert, creators of ENIAC’S. as US census bureau was already using IBCP cards, they were the pioneers in US buying this computer for the first time in 1951. the company created by M and ETS become UNIVAC division of Sperry and Corporation (later known as UNISYS).
Computer belonging to this generation had the following characteristics:
1. Comparatively large in size as composed to present day computers.
2. Generated lot of heat, they were not consistent and reliable as the valves tended to fall frequently.
3. low capacity internal storage.
4. individual, non-related models.
5. processors operated in the milliseconds speed range.
6. internal storage consisted of magnetic drum and delay lines.
Second Generation (1955-1964):
FGC were very unreliable, mainly because of vacuum tubes which kept on burning out. Users had to be prepared all the time with dizen of extra tubes to replace them. The computers of this generation were characterized by the use of Solid State devices(transistors) misted of vacuum tubes. Transistorized circuits were smaller, generated little heat, were expensive and consumed less power than vacuum tube circuits and were much greater in processing capacity.
Since transistors had a faster switching action, this generation than first generation computers. The use of magnetic cores as the primary internal storage medium and the introduction of removable magnetic disc pack were other major developments of the second generation. Although magnetic tapes were still used commonly. These computers had built in error detecting devices and more efficient means were developed to input and retrieve from the computer.
Some of the popular models in this generation of computer systems, we IBM-1401, IBM-1620, BURROUGHS B-200 SERIES, HONEY-WELL H-400, these computers were used for business applications.
Third Generation of Computer(1964-1975)
A revolution in the computer developments took place with the development of integrated circuits (IC) on a single silicon chip. In 1958, jack St Clair Kebly and Robert Noyce invented the first IC. IC incorporated number of transistors and electronic circuits on a single wafer or chip of silicon IC is called chip beause of the way they are made. They are also called as semi conductors as combining layers of materials that have varying capacity to conduct electricity from them.
This ushered in the third generation of computer systems in 1964. the integrated circuits enhanced considerably the processing capability of placing 12 or more logic gates on a single chip was developed into a well-defined technology was redefined to a point where hundreds or more gates could be placed on a chip of silicon and incorporated as functional logic block in an overall system.
Computers of this generation have the following characteristicts:
1. Smaller in size as compared to second generation computers.
2. Higher capacity internal storage.
3. Remote communication facilities.
4. Multiprogramming facilities.
5. Reduced cost of access storage.
6. Processors, which operate in nanosecond speed range.
7. Use of high level languages such as COBOL.
8. Wide range of optional peripherals.
Fourth Generation of Computer (1975-1989)
The 1970’s marked the beginning of a new generation of computers, produced by computer giants like IBM, ICL, CNR and Burrought. From design viewpoint, the new generation provided increased input-output capability, longer component life as well as greater system reliability. From the functional view point, new powerful language were developed to broaden the use of multiprogramming and multiprocessing and major shift from batch processing to on line, remote interactive processing.
The development of microprocessor chip, which contains an entire Central Processing Unit(CPU) on a single silicon chip led to the mushroom growth of inexpensive computers. They are not computers by themselves but they can perform all the functions of arithmetic logic unit and control units of the CPU. When these microprocessor are connected with memory and input-output devices, they become microcomputers.
The use of very large integrated circuits (VLSI) has made the froth generation (micro) computers very compact, much less expensive, faster, more reliable and of much greater data processing capacity than equalized third generation computers.
Some computers belonging to fourth generation are DEC-10, STAR-1000, PDP-11 AND APPLE Series Personal computers.
Fifth Generation Computers (1989-Present)
Till fourth generation of computers, the major stress was on improving the hardware from values to transistors and then to integrated circuits, which resulted in miniaturization and fast speed of computers. Hardware, the lack of thinking power has forced the scientists to work further for fifth generation computers.
The concept of “Artificial Intelligence” is being used in these computers and Japanese call them “Knowledge Processors”. Automatic programming, computational logic, pattern recognition and control of robots, the processes and which need skill and intelligence are examples of Artificial Intelligence. These computers, when developed, will have be able to execute billion of instructions per second and will have unimaginable storage capacities. The present day high level languages will become obsolete on these machines and new computer language and related software will be needed.
Computers of this generation have the following characteristics:
1.Easy to computers with high intelligence and natural human input and output mechanism;
2.Reliable and efficient software development by new languages, new computer architectures and systems software which overcome previous problems;
3.Improved overall functions and performance aimed at making computers smaller, lighter, faster, faster, of greater capacity, more flexible and more reliable
Introduction-The processing unit in a computer interest instructions given in a programs and carries out the instructions. Processors are designed to interpret a specified number of instruction codes. Each instruction code is a string of binary digits. All processors have input/outputs instructions, arithmetic instructions, to manipulate characters. The number and type of instructions available differ from processor to processor.
A memory or store is required in a computer to store programs and the data processed by programs. A memory is made up of a large number of cells, with each cell capable of storing one bit. The cells may be organized as a set of addressable words, each word storing a sequence of bits. In one such address of the word. This organization, called a Random Access Memory (RAM), is used as the main memory of computers. Another organization arranges cells in a linear sequence to from a serial access memory.
The Central Processing unit is the brain of the computers system. The input and output devices may vary for different application, but there is only one CPU for a particular computer. The specifications of a computer are basically characterized by its Central Processing Unit.The CPU processes the data it receives as input (either through input devices or through the memory). As mentioned earlier the CPU receives the data in the from of binary bits, which it can understand.
1. the CPU can perform arithmetic calculation such as addition, subtraction etc.
2. the CPU can perform logical decisions.
3. The CPU with the help of other devoices can perform data transmission.
4. The CPU can perform manipulating tasks such as word processing.
5. After performing the required task the CPU may place results in memory or send results to the output device according to the instruction given to it.
The central processing unit can be further divided into:
1. Arithmetic Logic Unit(ALU)-
As the name may indicate the arithmetic logic unit performs all arithmetic and logic calculations on the data it receives.
2. Arithmetic Calculations-
The arithmetic calculations may be addition, subtraction, multiplication, division, exponentiation etc.
3. Logical Calculation-
Logical calculations are basically decision making statements. For example, A>B, decides whether is A is greater B or not; IF A is greater than B the statement is true and logical ‘1’ would be generated, otherwise a logical ‘0’ would be generated. Some logical decide the further routing of the program.
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Labels: fundamentals of computer
Control Unit –
Control Unit –
The control unit controls the entire operations of the computer and the CPU. It controls all the other devices connected the CPU. Input devices, output devices, auxiliary Memory etc. hence, the control acts as the never centre of the computer.
The control unit upon receiving an instruction decides what is to be done with it. That is, whether it is to be sent to the ALU for further processing or to the output devices or to the memory etc. in other words the control unit coordinates and controls all hardware operations.
The control unit has an electronic clock that transmits electronic pulses at equal interval of time. The control unit gives instructions to other devices based upon these pulses. Suppose there are three instructions to be performed. Let the first instructions take three clock pulses to complete; when the fourth clock pulse is received the control unit would start processing the second instruction and so on. Suppose an instruction takes three and for the fourth clock pulse to complete and take up the next instruction with the fifth clock. Pulse.
Registers –
The CPU consists of a set of registers which are used for various operations during the execution of instructions. CPU needs registers for storing instructions as well as for storage and manipulation of temporary results.
1. Fetch: To bring the instructions from main memory into the instruction register.
2. Decode: Decoding means interpretation of the instruction to decide which course of action is to be taken for execution of the instruction and what sequence of control singles must be generated for it.
3. Execute: The instruction is execute after the fetching of operands is complete. The control unit is responsible for sequencing the steps necessary to complete.
Keyboard Devices:Most input data is entered input the computer by using a keyboard. This input methods is similar to typing on a typewriters.
Most typewriters and computer keyboards are Qwerty Keyboards. The alphabetic keys are arranged so that the upper-left row of letters begins with the six letters QWERTY. Designers of other keyboards claim that their boards are easier to learn than the QWERTY keyboard.
Computer keyboards
Include keys that are designed to perform specific tasks. These special keys include function keys, directional keys and special-purpose keys such as Alt, Ctrl, Enter, Ins, and Esc. These keys enable the user to perform complex tasks easily when using the application.
Some of keyboards have even 112 keys, with three new keys designed to simplify worki
Point and Draw Devices : Many people use devices instead of keyboards whenever possible. Pointing devices minimize the amount of typing (consequently, the number of errors). The many pointing devices available include the mouse, trackball, light pen, digitizing tablet, touch screen and pen-based systems.
The Mouse and Track Ball: The mouse is a palm-size device with a ball built into the button. The mouse is usually connected to the computer by the cable (computer wires are frequently called cables) and many have from one to four buttons (usually two). The mouse may be mechanical or optical and comes in many shapes and sizes. When you move the mouse over a smooth surface, the calls rolls, and the pointer on the display screen moves in the same direction. The Apple Macintosh, with its graphical user interface, made the mouse popular. Now, most microcomputer systems, regardless of the manufacturer, use a mouse. With the mouse, you can draw, select options from a menu and modify or move text. You issue commands by pointing with the pointer and clicking a operating a microcomputer easier for beginning users.
Touchpad:
The touch pad is a stationary pointing devices that people find less tiring to use than a mouse or a track ball. The movement of a finger across a small touch surface is translated into cursor movement on the computer screen. The touch sensitivity surface may be just 1.5- 2 inch square, so the finger does not have to move much. Its size makes it most suitable for the notebooks or the laptops.
A device
That was released in 1995 enables the user to move the cursor using and infrared pen. The pen is cordless and works when it is as fifteen feet from the screen. Although the mouse is still the most pointing device, these innovations may change that in future.
Joysticks:
A joysticks is a pointing device often used for playing games. The joystick has a gearshift-like lever that is used to move the pointer on the screed. On most joysticks, a button on the top is used to select options. In industry and manufacturing, joysticks are used to control robots. Flight simulators and other training simulators also use joysticks.
Touch-Sensitive Screens:
Perhaps the easiest way to enter data is with the touch of finger. Touch screens enable the user to select and option by pressing a specific part of the screen. Touch screens are commonly used in grocery stores, fast-food restaurants and information kiosks.
Optical Recognition System:
Optical Recognition System provide another means of minimizing keyed input by capturing data at the source. These systems enable the computer to “red” data by scanning printed text for recognizable patterns.
The banking industry developed one of the earliest scanning systems in the 1950’s for processing cheque. The Magnetic link Character Recognition (MICR) system is still used throughout the banking industry. The bank, branch, account number and cheque number are encoded on the cheque before it is sent to the customer. After the customer has used the cheque and it comes back to the bank to the bank, all that needs to be entered manually is the amount. MICRO has not been adopted by other industries because the character set has only fourteen symbols.
Bar Code Reader:
Of all the scanning devices, you are probably most familiar with BAR CODE READES. Many retail and grocery stores use some from of bar code reader to determine the item being sold and to retrieve the item price from a computer system. The code reader may be a handled unit or it may be embedded in a countertop. The bar code reader reads the Universal Product Code(UPC), a pattern of bars printed on merchandise. The UPS has gained the use of the code because the system was used to check their accuracy and speed. Today, bar codes are used to update inventory and ensure correct pricing. Federal Express employees can usually tell a customer within a matter of minutes the location of any package.
Optical Mark Reader:
By taking exams, you are familiar with Mark Sense Character Recognition systems. Every time you take a test with a “fill in the bubble” Scranton from and use a #2 lead pencil, you are creating input suitable for and OPTICAL MARK READER (ORMO. A #2 lead pencil works best because of the number of magnetic particles in that weight lead. The OMR sense the magnetized marks, enabling the reader to determine which responses are marked.
Optical Scanners:
Can scan typed documents, pictures, graphics or even handwriting into a computer. Photographs scanned into a microcomputer appear clearly on the screen and can be displayed whenever desired. The copy that the computer stores never yellows with age. Early scanners could recognize only text printed in a special OPTICAL CHARACTER RECOGNITION(OCR) typeface. A scanner converts the image that it sees into numeric digits before storing it in the computer. This conversion process in known as DIGIZING.
Depending on the volume and type of material to be scanned, you can use drum scanner, flatbed scanner, sheeted scanner and even small handheld scanners. The small, hadheld scanner sheeted scanners(priced at about $150) are used most frequently with micro microcomputer; however, only 5 per cent of all microcomputer systems are equipped with scanners. Manufacturers responded to user reluctance to use scanners by releasing in 1995 a number of new, small paper scanners priced between $500 and $700.) most of these new devices sit between the keyboard and the monitor and can interface with a fax machine, send e-mail, and store documents on disk for archive purposes.
Digitizer:
Digitizer is used to create drawing and pictures using a digitizer tablet by a process called digitizing. Digitizing is a process by which graphic representations are converted into digitizer consist of 3 main parts – a flat surface called tablet, a small hand held mouse-like device called puck and a special pen like device called stylus. The puck is used to input existing drawings into the computer. The stylus is used to trace exiting drawing placed on the tablet. The user makes contact to the tablet with stylus. As the stylus is connected to the tablet by a write, the traced image is stored in RAM and displayed on the monitor.
Electronic Card Reader:
Before discussing electronic card reader, let we discuss electronic credit cards. Electronic credit card make it possible to charge online payments to one’s credit card account. It is card details can be encrypted by using the SSL. Protocol in the buyer’s computer, which is available in standard browsers. The number of input devices are common in association with ash transactions. The most common are ATMs and POS terminals.
1. ATM:
Automatic Taller Machine are interactive input/output devices the enable people to make bank transactions from remote locations. ATMs utilize screen input as well as magnetic card readers.
2. POS:
Point of Sale: terminals are computerized cash registers that also often incorporate touch screen technology and bar-code scanners. These devices allow the input of numerous data such as item sold, price, method of payment, name or Zip code of the buyer, and so on. Some inputs are automated; others may be entered by the operators.
Vision Input System:
Are the latest input devices that can recognize the vision/image which appears in the range of its lens. It seems to be vary useful and are becoming popular in different Got. Departments like licensing, passport department and other authorities where personal identification is required.
Plotter
Plotter
is an important output device. Used to print high quality graphics and drawings. Although the graphics can be printed on printers, the resolution of such printing is limited on printers. Plotters are generally used for printing/drawing graphical images such as charts, drawings, maps. Of engineering and scientific application.
Some important types of printers are:
a.) Flat Bed Plotters:
These plotters print the graphical images by moving the pen on stationary flat surface material. They produce very accurate drawings.
b.) Drum Plotters:
These plotters print graphical images by moving both the pen and the drum having paper. They do not produce as accurate drawings as printed by flat bed plotters.
c.)Inkjet Plotters: These plotters use inkjet in place of pens. They are faster than flat bed plotters and can print multi-colored large drawings.
Your computer system consists of thousands of individual components that work in harmony to process data. Each of these components has its own job to perform, and each has its own performance characteristics.
The brainpower of the system is the Central Processing Unit(CPU), which processes all the calculations and instructions that run on the computer. The job of the rest of the system is to keep the CPU busy with instructions to process. A well-tuned system runs at maximum performance if the CPU or CPU are busy 100% of the time.
So how does the system keep the CPUs busy? In general, the system consists of different layers, or tiers, of progressively slower components. Because faster components are typically the most expensive, you must perform a balancing act between speed and cost efficiency.
CPU and Cache
The CPU and the CPU’s cache are the fastest components of the system. The cache is high-speed memory used to store recently used data instructions so that it can provide quick access if this data is used again in a short time. Most CPU hardware designs have a cache built into the CPU chip. This internal cache is known as a Level 1 (or L1) cache. Typically, an L1 cache is quite small-8-16KB.
When a certain piece of data is wanted, the hardware looks first in the L1 cache. If the data is there, it’s processed immediately. If the data is not available in the cache, the hardware looks in the L2 cache, which is external to the CPU chip but located close to it. The L2 cache is connected to the CPU chip(s) on the same side of the memory bus as the CPU. To get to main memory, you must use the memory bus, which affects the speed of the memory access
CPU Design
Most instructions processing occurs in the CPU. Although certain intelligent devices, such as disk controllers, cam process some instruction, the instructions these devices can handle are limited to the control of dada moving to and from the devices. The CPU works from the determine how quickly these instructions are executed.
The CPU usually falls into one of two groups process:
Complex Instructions Set Computer(CISC) or
Reduced Instructions Set Computer(RISC).