We are going to define a computer, and yes, all the devices you see in the slide are computers, some more specialized than others, but all computers.

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2 We are going to define a computer, and yes, all the devices you see in the slide are computers, some more specialized than others, but all computers. A computer is a general-purpose device that can be programmed to carry out a set of arithmetic or logical operations automatically. This sequence of operations, called a computer program, can be readily changed, and this way the computer can solve many different problems. All the computers that we know today are digital electronic computers based on microprocessors, but there was a time when the computers were mechanical devices. Digital Computers work in binary system, they only store and operate with 1s and 0s, we will see how, using this simple system, they can achieve such wonderful things. 2

3 Computers store and process data to generate useful information. Usually data is used to refer to raw or unprocessed data and the information to the results we get after processing it. The information obtained in one processing stage can be fed as raw data to the next processing cycle to get new information. 3

4 When you think of a computer, an electronic device comes to your mind. But this electronic device is useless without the programs that make it work, so the computer definition includes the electronic device and its components, called hardware, and the programs that control it, that are called software. The software can be compared with the instruction booklet of a ready-to-assemble furniture, as it has step-by-step assembly instructions that guide all the assembly process. 4

5 Computer hardware includes all the physical components of a computer system, either located inside the system unit or outside it (in which case the components are know as peripherals): the keyboard, mouse and other input devices the CPU, memory and other chips needed to connect all the components (that are known as processing devices) the monitor, printer and other output devices the hard disk, DVD unit, and flash memory drives used to store permanently the results the communication devices used to connect to a local or remote network, like network cards or modems and all the support electronic needed to make the system run (power supply, cable buses, cooling fans, etc..). In the beginnings of personal computing, installing new hardware in our computer could be a nightmare, as, usually, some hardware configuration was necessary (as changing microswitches, for example) and the execution of one or several configuration programs was required. Today, most hardware devices and modern personal computer operating systems include some form of plug&play capabilities, that manage automatically most or all the processes needed to configure a new hardware added to a personal computer. Manual hardware installation is something that you will have to do in some occasions only if you are using some of the operating systems derived from UNIX, as some LINUX distributions. Computer hardware gets obsolete very fast and, given some materials used in its manufacturing, can be a big source of waste and pollution. There are several initiatives to try to minimize or eliminate the impact on the environment of designing, manufacturing, using, and disposing of computers, servers, and associated subsystems. These are commonly known as Green computing, Green ICT, Green IT or ICT sustainability. 5

6 A computer is useless without a computer program that instructs it how to process data and manage devices. Computer software allows computers to perform specific tasks or applications. In a computer we can find two types of software: system software and application software. The main system software is the operating system, that is loaded when the computer starts and manages the interaction of the user and all application software with hardware devices, their access to files and orchestrates the execution of different programs. The other type of software is application software. This software is created to develop a specific task, as word processing, creating spreadsheets, designing slide shows, calculating the stresses of a building or browsing the Internet. As described with hardware, installing a new software in the early days of computing could be a tricky task. Nowadays most software programs are distributed with an automated tool called installation wizard that guides the user through the installation process. 6

7 All computers work following an information processing cycle know as IPOS, acronym formed by the initials of Input-Processing-Output-Storage First the computer needs that data is entered into the system (Input). For this the computer has is specific hardware known as input devices (for example a keyboard or a scanner) -Then the computer performs some operations on the data (Process) using its Central Processing Unit or CPU After finishing the computer presents the results to the user (Output). For this it uses specific hardware called output devices (as the computer monitor or the printer) The results can be stored for future use (Storage) (saving data, programs, or output for future use). For this the computer has permanent storage devices as the internal hard disk or the removable devices as pen-drives. These storage devices have input and output functions. 7

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