@2012 by Pedernal Jemerson G. Pedernal Jemerson G ICT Network Specialist Palawan State University

Chapter 2 What is a Computer? The word computer comes from the word compute”, which means, “to calculate” Thereby, a computer is an electronic device that can perform arithmetic operations at high speed A computer is also called a data processor because it can store, process, and retrieve data whenever by Pedernal Jemerson G.

Data Processing The activity of processing data using a computer is called data processing. Data Capture Data Manipulate Data Output Results Information Data is raw material used as input and information is processed data obtained as output of data processing

Characteristics of Computers 1.Automatic: Given a job, computer can work on it automatically without human interventions 2.Speed: Computer can perform data processing jobs very fast, usually measured in microseconds (10 -6 ), nanoseconds (10 -9 ), and picoseconds ( ) 3.Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. Computer errors caused due to incorrect input data or unreliable programs are often referred to as Garbage-In-Garbage-Out by Pedernal Jemerson G.

Characteristics of Computers 4.Diligence: Computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling 5.Versatility: Computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps 6.Power of Remembering: Computer can store and recall any amount of information because of its secondary storage capability. It forgets or looses certain information only when it is asked to do by Pedernal Jemerson G.

Characteristics of Computers 7.No I.Q.: A computer does only what it is programmed to do. It cannot take its own decision in this regard 8.No Feelings: Computers are devoid of emotions. Their judgement is based on the instructions given to them in the form of programs that are written by us (human by Pedernal Jemerson G.

Computer Classification A.personal computer: a small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data.personal computeruser microprocessormonitorstorage devicesaving B.workstation: a powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.workstation C.minicomputer: a multi-user computer capable of supporting from 10 to hundreds of users simultaneously.minicomputermulti-user D.mainframe: a powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.mainframe E.supercomputer: an extremely fast computer that can perform hundreds of millions of instructions per by Pedernal Jemerson G.

Modern Computers Modern computers are electronic and digital. digital The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called software. transistorshardwaredata by Pedernal Jemerson G.

Modern Computers (Cont.) All general-purpose computers require the following hardware components: memory: enables a computer to store, at least temporarily, data and programs.memorystore mass storage device: allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.mass storagedevicedisk drivestape drives input device: usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.input devicekeyboardmouse output device: a display screen, printer, or other device that lets you see what the computer has accomplished.output devicedisplay screenprinter central processing unit (CPU): the heart of the computer, this is the component that actually executes instructions.central processing by Pedernal Jemerson G.

Modern Computers (Cont.) In addition to these components, many others make it possible for the basic components to work together efficiently. For example, every computer requires a bus that transmits data from one part of the computer to by Pedernal Jemerson G.

Evolution of Computers Blaise Pascal invented the first mechanical adding machine in 1642 Baron Gottfried Wilhelm von Leibniz invented the first calculator for multiplication in 1671 Keyboard machines originated in the United States around 1880 Around 1880, Herman Hollerith came up with the concept of punched cards that were extensively used as input media until late by Pedernal Jemerson G.

Evolution of Computers (Cont.) Charles Babbage is considered to be the father of modern digital computers He designed “Difference Engine” in 1822 He designed a fully automatic analytical engine in 1842 for performing basic arithmetic functions His efforts established a number of principles that are fundamental to the design of any digital by Pedernal Jemerson G.

Some Well Known Early Computers 1.The Mark I Computer ( ) 2.The Atanasoff-Berry Computer ( ) 3.The ENIAC ( ) 4.The EDVAC ( ) 5.The EDSAC ( ) 6.Manchester Mark I (1948) 7.The UNIVAC I by Pedernal Jemerson G.

Unit Quiz Get ¼ sheet of Yellow Paper Enumeration Type Quiz Write the following on top of your paper Do not erase you answer, erasure will be considered as wrong by Pedernal Jemerson G. Your Full NameDate Your Course/Year/BlockUnit 2 Quiz

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