Jumaat, 20 Januari 2012
COMPUTER OF CLASSIFICATION
Until recently computers were classifieds as microcomputers, super minicomputers, mainframes, and supercomputers. Technology, however, has changed and this classification is no more relevant. Today all computers used microprocessors as their CPU. Thus classification is possible only through their mode of use. Based on mode of use we can classify computers as Palms, Laptop PCs, Desktop PCs and Workstations. Based on interconnected computers we can classify computers we can classify them as distributed computers and parallel computers.
Laptop PCs (also known as notebook computers) are portable computers weighing around 2 kgs. They have a keyboard, flat screen liquid crystal display, and a Pentium or Power PC processor. Colour displays are available. They normally run using WINDOWS OS. Laptops come with hard disk (around 40 GB), CDROM and floppy disk. They should run with batteries and are thus designed to conserve energy by using power efficient chips. Many Laptops can be connected to a network. There is a trend towards providing wireless connectivity to Laptops so that they can read files from large stationary computers. The most common use of Laptop computers is used for word processing, and spreadsheet computing. As Laptops use miniature components which have to consume low power and have to be packaged in small volumes.
While manufacturers such as IBM, SUN and Silicon Graphics have been manufacturing high performance workstations the speed of Intel Pentium Processors has been going up. In 2004, Pentium with clock speed 3 GHz are available. They can support several GB main memories. Thus the difference between high end PCs and Workstations is vanishing. Today companies such as SUN make Intel based workstations.While Workstations are characterized by high performance processors with large screens for interactive programming, servers are used for specific purpose such as high performance numerical computing (called compute server), web page hosting, database store, printing etc. interactive large screens are not necessary. Compute servers have performance processors with large main memory, database servers have big on-line disk storage (100s of GB) and print servers support several high speed printers.
Palm PCs or Simputer
With miniaturization and high-density packing of transistor on a chip, computers with capabilities nearly that of PCs which can be held in a palm have emerged. Palm accept handwritten inputs using an electronic pen which can be used to write on a Palm’s screen (besides a tiny keyboard), have small disk storage and can be connected to a wireless network. One has to train the system on the user’s handwriting before it can be used as a mobile phone, Fax, and e-mail machine. A version of Microsoft operating system called Windows-CE is available for Palm.An Indian initiative to meet the needs of rural population of developing countries is called Simputer. Simputer is a mobile handheld computer with input through icons on a touch sensitive overly on the LCD display panel. A unique feature of Simputer is the use of free open source OS called GNU/Linux. The cost of ownership is thus low as there is no software cost for OS. Another unique feature of Simputer not found in Palm, is a smart card reader/writer, which increases the functionality of the Simputer including possibility of personalization of a single Simputer for several users.Laptop PCs:
Laptop PCs (also known as notebook computers) are portable computers weighing around 2 kgs. They have a keyboard, flat screen liquid crystal display, and a Pentium or Power PC processor. Colour displays are available. They normally run using WINDOWS OS. Laptops come with hard disk (around 40 GB), CDROM and floppy disk. They should run with batteries and are thus designed to conserve energy by using power efficient chips. Many Laptops can be connected to a network. There is a trend towards providing wireless connectivity to Laptops so that they can read files from large stationary computers. The most common use of Laptop computers is used for word processing, and spreadsheet computing. As Laptops use miniature components which have to consume low power and have to be packaged in small volumes.
Personal Computers (PCs)
The most popular PCs are desktop machines. Early PCs had Intel 8088 microprocessors as their CPU. Currently (2004), Intel Dual Core is the most popular processor. The machines made by IBM are called IBM PCs. Other manufacturers use IBM’s specifications and design their own PCs. They are known as IBM compatible PCs. IBM PCs mostly use MS-Windows, WINDOWS –XP or GNU/Linux as Operating System. IBM PCs, nowadays (2004) have 64 to 256 MB main memory, 40 to 80 GB of Hard Disk and a floppy disk or flash ROM. Besides these a 650 MB CDROM is also provided in PCs intended for multimedia use. Another company called Apple also makes pCs. Apple PCs are known as Apple Macintosh. They use Apple’s proprietary OS, which is designed for simplicity of use. Apple Macintosh machines used Motorola 68030 microprocessors but now use Power PC 603 processor. IBM PCs are today the most popular computers with millions of them in use throughout the world.Workstations:
Workstations are also desktop machines. They are, however, more powerful providing processorspeeds about 10 times that of PCs. Most workstations have a large colour video display unit (19 inch monitors). Normally they have main memory of around 256 MB to 4 GB and Hard Disk of 80 to 320 GB. Workstations normally use RISC processors such as MIPS (SIG), RIOS (IBM), SPARC (SUN), or PA-RISC (HP). Some manufacturers of Workstations are Silicon Graphics (SIG), IBM, SUN Microsystems and Hewlett Packard (HP). The standard Operating System of Workstations is UNIX and its derivatives such as AIX (IBM), Solaris (SUN), and HP-UX (HP). Very good graphics facilities and large video screens are provided by most Workstations. A system called X WINDOWS is provided by Workstations to display the status of multiple processes during their execution. Most Workstations have built-in hardware to connect to a Local Area Network (LAN). Workstations are used for executing numeric and graphic intensive applications such as those, which arise in Computer Aided Design, simulation of complex systems and visualizing the results of simulation.
Servers
While manufacturers such as IBM, SUN and Silicon Graphics have been manufacturing high performance workstations the speed of Intel Pentium Processors has been going up. In 2004, Pentium with clock speed 3 GHz are available. They can support several GB main memories. Thus the difference between high end PCs and Workstations is vanishing. Today companies such as SUN make Intel based workstations.While Workstations are characterized by high performance processors with large screens for interactive programming, servers are used for specific purpose such as high performance numerical computing (called compute server), web page hosting, database store, printing etc. interactive large screens are not necessary. Compute servers have performance processors with large main memory, database servers have big on-line disk storage (100s of GB) and print servers support several high speed printers.
Mainframes Computers
There are organizations such as banks and insurance companies process large number of transactions on-line. They require computers with very large disks to store several Terabytes of data and transfer data from disk to main memory at several hundred Megabytes/sec. The processing power needed from such computers is hundred million transactions per second. These computers are much bigger and faster than workstations and several hundred times more expensive. They normally use proprietary operating systems, which usually provide high expensive services such as user accounting, file security and control. They are normally much more reliable when compared to Operating System on PCs. These types of computers are called mainframes. These are a few manufacturers of mainframes (e.g., IBM and Hitachi). The number of mainframe users has reduced as many organizations are rewriting their systems to use networks of powerful workstationsSupercomputers
Supercomputers are the fastest computers available at any given time and are normally used to solve problems, which require intensive numerical computations. Examples of such problems are numerical weather prediction, designing supersonic aircrafts, design of drugs and modeling complex molecules. All of these problems require around 10^16calculations to be performed. These problems will be solved in about 3 hours by a computer, which can carry out a trillion floating point calculations per second. Such a computer is classifieds as supercomputer today (2004). By about the year 2006 computers which can carry out 10^15 floating point operations per second on 64 bit floating point numbers would be available and would be the ones which be called supercomputers. Interconnecting several high speed computers and programming them to work cooperatively to solve problems build supercomputers. Recently applications of supercomputers have expanded beyond scientific computing, they are now used to analyze large commercial database, produced animated movies and play games such as chess.Besides arithmetic speed, a computer to be classified as a supercomputer should have a large main memory of around 16 GB and a secondary memory of 1000 GB. The speed of transfer of data from secondary memory to the main memory should be at least a tenth of the memory to CPU data transfer speed. All supercomputers use parallelism to achieve their speed. In Sec. 12.9 we discuss the organization of parallel computers
COMPUTER HISTORY AND GENERATIONS
In the beginning ...
A generation refers to the state of improvement in the development of a product. This term is also used in the different advancements of computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and memory of computers has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.
The First Generation: 1946-1958 (The Vacuum Tube Years)
The first generation computers were huge, slow, expensive, and often undependable. In 1946two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I. The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do. The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer).
The vacuum tube was an extremely important step in the advancement of computers. Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs. It's purpose was to act like an amplifier and a switch. Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it). Vacuum tubes could also stop and start the flow of electricity instantly (switch). These two properties made the ENIAC computer possible.
The Second Generation: 1959-1964 (The Era of the Transistor)
The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology. In 1947 three scientists, John Bardeen, William Shockley, and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever. This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.
There were obvious differences between the transisitor and the vacuum tube. The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. One transistor replaced the equivalent of 40 vacuum tubes. These transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass. Therefore they were very cheap to produce. Transistors were found to conduct electricity faster and better than vacuum tubes. They were also much smaller and gave off virtually no heat compared to vacuum tubes. Their use marked a new beginning for the computer. Without this invention, space travel in the 1960's would not have been possible. However, a new invention would even further advance our ability to use computers.
The Third Generation: 1965-1970 (Integrated Circuits - Miniaturizing the Computer)
Transistors were a tremendous breakthrough in advancing the computer. However no one could predict that thousands even now millions of transistors (circuits) could be compacted in such a small space. The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon. Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently discovered the amazing attributes of integrated circuits. Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.
Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power. Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of bakelite or fiberglass that have electrical connections etched onto them -- sometimes called a mother board.
These third generation computers could carry out instructions in billionths of a second. The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered.
A generation refers to the state of improvement in the development of a product. This term is also used in the different advancements of computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and memory of computers has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.
The first generation computers were huge, slow, expensive, and often undependable. In 1946two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I. The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do. The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer).
The vacuum tube was an extremely important step in the advancement of computers. Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs. It's purpose was to act like an amplifier and a switch. Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it). Vacuum tubes could also stop and start the flow of electricity instantly (switch). These two properties made the ENIAC computer possible.
The Second Generation: 1959-1964 (The Era of the Transistor)
The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology. In 1947 three scientists, John Bardeen, William Shockley, and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever. This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.
There were obvious differences between the transisitor and the vacuum tube. The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. One transistor replaced the equivalent of 40 vacuum tubes. These transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass. Therefore they were very cheap to produce. Transistors were found to conduct electricity faster and better than vacuum tubes. They were also much smaller and gave off virtually no heat compared to vacuum tubes. Their use marked a new beginning for the computer. Without this invention, space travel in the 1960's would not have been possible. However, a new invention would even further advance our ability to use computers.
The Third Generation: 1965-1970 (Integrated Circuits - Miniaturizing the Computer)
Transistors were a tremendous breakthrough in advancing the computer. However no one could predict that thousands even now millions of transistors (circuits) could be compacted in such a small space. The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon. Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently discovered the amazing attributes of integrated circuits. Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.
Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power. Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of bakelite or fiberglass that have electrical connections etched onto them -- sometimes called a mother board.
These third generation computers could carry out instructions in billionths of a second. The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered.
The Fourth Generation: 1971-Today (The Microprocessor)
This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer). By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers. Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.
This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer). By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers. Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.
However what really triggered the tremendous growth of computers and its significant impact on our lives is the invention of the microprocessor. Ted Hoff, employed by Intel (Robert Noyce's new company) invented a chip the size of a pencil eraser that could do all the computing and logic work of a computer. The microprocessor was made to be used in calculators, not computers. It led, however, to the invention of personal computers, or microcomputers.
It wasn't until the 1970's that people began buying computer for personal use. One of the earliest personal computers was the Altair 8800 computer kit. In 1975 you could purchase this kit and put it together to make your own personal computer. In 1977 the Apple II was sold to the public and in 1981 IBM entered the PC (personal computer) market.
Today we have all heard of Intel and its Pentium® Processors and now we know how it all got started. The computers of the next generation will have millions upon millions of transistors on one chip and will perform over a billion calculations in a single second. There is no end in sight for the computer movement.
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