Computer Components Computers come in all types and sizes. There are primarily two main sizes of computers. They are: Portable Desktop The portable computer comes in various sizes and are referred to as laptops, notebooks, and hand-held computers. These generally denote different sizes, the laptop being the largest, and the hand-held is the smallest size. This document will mainly talk about the desktop computer although portable computer issues are also discussed in various areas. Computer Components: Computers are made of the following basic components: Case with hardware inside: Power Supply - The power supply comes with the case, but this component is mentioned separately since there are various types of power supplies. The one you should get depends on the requirements of your system. This will be discussed in more detail later Motherboard - This is where the core components of your computer reside which are listed below. Also the support cards for video, sound, networking and more are mounted into this board. Microprocessor - This is the brain of your computer. It performs commands and instructions and controls the operation of the computer. Memory - The RAM in your system is mounted on the motherboard. This is memory that must be powered on to retain its contents. Drive controllers - The drive controllers control the interface of your system to your hard drives. The controllers let your hard drives work by controlling their operation. On most systems, they are included on the motherboard, however you may add additional controllers for faster or other types of drives. Hard disk drive(s) - This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here. CD-ROM drive(s) - This is normally a read only drive where files are permanently stored. There are now read/write CD-ROM drives that use special software to allow users to read from and write to these drives. Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4 Megabytes of memory capacity. Other possible file storage devices include DVD devices, Tape backup devices, and some others. Monitor - This device which operates like a TV set lets the user see how the computer is responding to their commands. Keyboard - This is where the user enters text commands into the computer. Mouse - A point and click interface for entering commands which works well in graphical environments. These various parts will be discussed in the following sections.

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.

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 workstations.

Supercomputers

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

HISTORY OF COMPUTERS

This is a searchable directory about the history of computers, computing and a timeline of the history of computers and early calculating machines has been included. Our timeline includes developments in the 1600's and their impact on computing. The development of the modern day computer was the result of advances in technologies and man's need to quantify. (The abacus was one of the first counting machines. Calculating machines were sold commercially before the advent of steel manufacturing technologies. Papyrus was something to write on, before we had paper. Writing was a way to record mathematical calculations.) This history of computers site includes the names of early pioneers of math and computing and links to related sites for further study. A new "Timeline of the History of Computers and Related Technologies" has been added. This site was designed to be used by students assigned topics about the history of computers and computing. Original articles are footnoted and related links are included. One important purpose of this Web page, is to debunk myths some people create, such as "we have computers because of the military" (Not true). We have computers because man wanted to quantify as early as the ancient Chinese Dynasties, when they created the abacus and used it for calculating, and adding and subtracting in particular... Babbage and Lovelace were "programming" machines as early as the 1800's before any military computer in this country. 1801 was the creation of the Jacquard loom which used "punch cards". Cathode Ray Tubes (CRTs) have been around since 1885 and the US gov't first used a computer in the 1950's. Great Britain's COLOSSUS was developed before the ENGIGMA, so people trying to perpetuate the importance of the US military in the development of computer technologies is doing a disservice to students. Electronics and related computer development, and the invention of the transistor were all independent of military intent. If anything, even the totalisator machines were created for statistical purposes and have been used for horse racing, not rocket science. I love my Mac, and it has no military background that I am aware of. Military computers did not have integrated circuits like PC computer chips either... Stop saying computer development was military in origin... simply can't back it up with fact. Yes, the military also had old computers, just like my Commodore was old... but they weren't related... no tubes in my commodore, that was different technology altogether than a military

GENERATIONS

First Generation (1940-1956) Vacuum Tubes

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.

Second Generation (1956-1963) Transistors

Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.

Third Generation (1964-1971) Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.

Fourth Generation (1971-Present) Microprocessors

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.

Fifth Generation (Present and Beyond) Artificial Intelligence

Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.onster computer with vacuum tubes... mechanical relays... ta dah... that was hot stuff in that age.