By: Mandip Gill I.T 9

 Computers started with the development of the abacus several thousand years ago  The abacus lets us do computations fast by sliding beads arranged on a rack; this has been around for thousands of years  Later, machines of different sorts eventually replaced early mechanical tools like the abacus  In 1642, Blaise Pascal invented a numerical wheel calculator to help his father who was a French tax collector to compute taxes each citizen owed  The Pascaline used a system of movable dials to add numbers with as many as eight digits  In 1812, Charles Babbage began to develop a machine called the Difference Engine which was intended to have a stored program and to perform calculations and print the results, but after 10 years of work, he left this machine and started working on a more better and revised one: the Analytical Engine  In 1820, Charles Xavier Thomas de Colmar invented the arithometer, a mechanical calculator that was able to perform the four basic mathematical functions: addition, subtraction, multiplication, and division  The arithometer was improved many times and it was used a lot until World War I  Herman Hollerith worked for the U.S. Census Bureau in 1889 and before in 1880 it had taken 7 years to count the census  Then Hollerith invented a quicker way to count the census which only took 6 weeks

 These modern computers were introduced during World War II  In England, a device called Colossus was made to decode encrypted German messages and that was the only thing it did but it was a marvel to the Allies and they had an advantage in war  The U.S. Army Ordnance Department and the University of Pennsylvania together developed the ENIAC  The project to develop ENIAC started in 1943 and was completed in 1946  It was difficult to operate but the ENIAC could perform calculations faster than any other calculating device that existed then  It could calculate a 60-second trajectory in 30 seconds  The ENIAC weighed over 30 tons, contained 19,000 transistor tubes, 1,500 relays, and consumed nearly 200 kilowatts of power  The ENIAC eventually gave way to more powerful computers  The EDVAC, designed by John Von Neumann had a central processing unit  The UNIVAC, built by Remington Rand was the first commercially computing device available

 Starting about 1956, the second generation of computers was marked by the shift from large, bulky, failure-prone vacuum tubes to transistors  Transistors use an electric charge, allowing it to alternate between an insulator and a conductor  As a conductor, the transistor is said to be in an "on" state letting another current to pass through it, and as an insulator, the current is stopped, placing the transistor in an "off" state  Transistors paved the way for much smaller, faster computers  Early supercomputers were used by atomic energy laboratories and the U.S. Navy Research and Development center to do the hard calculations associated with atomic weapons research  During this time, printers, disk and tape storage, memory and stored programs allowed computers to become multifunctioning devices,  Computer programming also changed during this time  Machine language (a system of 1s and 0s that communicates instructions directly to the computer's hardware) gave way to assembly languages  An assembly language uses human readable codes, to represent a series of 1s and 0s and each assembly instruction goes along with one machine-language instruction  As time passed, computer scientists invented high-level languages such as COBOL used in writing programs for business use, and FORTRAN used in writing programs for scientific research

 Jack Kilby and Robert Noyce invented the integrated circuit (IC) in the late 1950’s  They produced much less heat than transistors  Less heat allowed more components to fit into a single chip  A chip is a semiconducting substance (such as silicon), made in a tiny package that looks like a thin wafer  Microchips have allowed computers to shrink to the size of today’s laptop computers, which have more power than their enormous ancestors  Computers have become even smaller and more reliable

 Computers became readily available (in terms of size, cost, and reliability) to smaller businesses, and eventually to people  The first (PC) appeared in 1974  In the following years, the Apple I and II and the Commodore PET, were introduced  By 1990, 65 million PCs were in use  20 years after the first PCs, 1 billion personal computers were in use worldwide  While computer hardware was evolving, computer software and operating systems were too  Computers allow us to do many things, It is hard to imagine our world without them

 Hardware is the physical components of the computer  The principal concepts and technology behind this hardware remain essentially the same  The most popular and most used input devices include the keyboard and mouse, and there are other technologies that are used too  It would be nearly impossible to work with computers without input and output devices  Input devices allow you to enter information so that the computer can do the work it is designed to do  Without output devices, we would have no idea whether the computer was doing the right thing  Output is feedback; it lets us know what is happening on the inside of the computer  Today, the most common output device is your computer monitor  Another modern output device is the printer

 The single most important component of a computer is the central processing unit (CPU)  The CPU is basically the brains of the computer  The CPU performs very basic functions but performs these operations millions and even billions of times every second  Transistors lie at the heart of the CPU and they can be in either one of two states, on (when they are conducting electricity) and off (when they are not conducting electricity)  The CPU has no memory, it forgets the last calculation and starts the new one  Random-access memory (RAM) is a storage unit for data going to and coming from the CPU  RAM can hold a large quantity of data, but it can't store it long-term  Whenever you turn your computer off, all the information stored in RAM is lost and gone  Even when the computer is on, data stored in RAM are being changed and updated quickly

 To store data long term your computer uses hard drives, CD-ROMs, and floppy disks  Each of these uses different techniques for storing and retrieving data  Storage capacity is a measure of how many bits of data the medium can store  The primary storage device in a computer is the hard drive  Hard drives store data on a series of magnetic recording platters made of high- precision aluminum or glass  Hard drives are not portable from one computer to another  A storage device in use today, the recordable CD (CD-R), records data onto a disk  Other types of removable storage include optical drives, Zip drives, and USB drives

 Networking is the most explosive growth area of the computer industry  Networks connect computers together to share files, programs, and other resources  Media are the physical connections that join all the network’s parts so they can communicate  Most networks use a sort of cabling, such as a twisted-pair wire or coaxial cable and the growing number of networks transmit data by wireless links  The media connects the network to the individual computers, which are called nodes and each one contains a network interface card (NIC)

 Operating Systems(OS), often called platforms do two important jobs  They manage the hardware and software on your computer system and provide a consistent interface for applications  Operating systems fall into many categories, single user, multitasking, and multiuser and the one most know about is the single user, multitasking operating system  In this system, a user can tap the resources of a single computer to perform multiple tasks, mostly at the same time and MacOS and Windows are examples  Multiuser operating systems, allow multiple users to tap resources of a single, powerful computer and each user must have sufficient resources available to meet his or her needs  Examples of operating systems include UNIX/Linux, MacOS, and DOS/Windows

 The type of software that you buy at a nearby computer store is generally called desktop software  Desktop hardware runs on minimal hardware, and usually must be installed on the computer to run  Desktop software is categorized by the type of function it serves and there are database applications, word processing applications, image editing applications, and utility applications and each group may have many divisions in it  Some software does not run on your computer at all and web applications can run entirely on a Web server and you can access this through a standard Web browser  The line between desktop applications and Web-based applications is blurring fast  Web services provide applications with a standardized way of exchanging information across the Internet