Page1 Module 1: Computer Systems A. Introduction to Computers Computer is an electronic device which consists of several components that together provide the capability of executing stored program. It is a device that accepts data, processes and stores these, and produces a result. It performs four basic functions such as input, process, storage and output. The activity of processing data using a computer is called data processing. Figure 1 shows the flow of basic functions of a computer. Information Processing System Data is a collection of independent and unorganized facts. Information is the processed and organized data presented in a meaningful form. Data Processing is the course of doing things in a sequence of steps. Functions of an Information Processing System 1) It accepts and gathers data. (INPUT) 2) It processes data to become information. (PROCESSING) 3) It stores data and information. (STORE) 4) It presents information. (OUTPUT) Three Major Components of an Information Processing System Hardware is the tangible part of a computer system. It refers to the physical components of a computer that you can actually touch, such as the keyboard, monitor, central processing unit (CPU), mouse and printer. Software is the non-tangible part that tells the computer how to do its job. It is a set of instructions used to direct the hardware on how to turn data into useful information for people to use. These are programs used by the user to interact with the computer. Peopleware refer to people who use and operate the computer system, write computer programs, and analyze and design the information system. Data INPUT OUTPUT PROCESSOR STORAGE Information Fig. 1 Basic Computer Functions
Page2 Types of Computers Super Computers are most powerful and expensive. They have extremely large storage capacities and processing speed which is at least 10 times faster than other computers. It can calculate about 400 million numbers every second, and result is always exactly correct. Mainframe Computers are medium or large machines, powerful, expensive computers made of several units connected together. Mainframe computers are generally used in big organizations and government departments for large-scale data processing. Their processing capabilities vary from computers to computers ranging to millions of bytes per second. Mini Computers are like small mainframes, they consist of a few separate units connected together. Minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the large multi-user systems and the smallest single-user systems. Microcomputers or Personal Computer (PC) are the most common type of computers in existence today, whether in a workplace, at school or on the desk at home. The term microcomputer was introduced with the advent of single chip microprocessors. These computers include Desktop computers, Laptops, notebook computers, Smart phones and PDAs (personal digital assistants). History of Computing The table below traces the milestones in the development of computers. Table 1 Computer History Timetable Year Development 2000 B.C. Abacus The abacus gained popularity fast after it was invented. It is an instrument used in performing arithmetic calculations. It consists essentially of a tablet or frame bearing parallel wires or grooves on which counters or beads are moved. A modern abacus consists of a wooden frame with beads on parallel wires, and a crossbar oriented perpendicular to the wires that divides the beads into two groups. 1617 Logs and Bones John Napier, a Scottish mathematician became famous for his invention on logarithms. It reduced problem of subtraction. In 1617, he invented a computing device using a set of sticks called bones which can perform both multiplication and division. 1642 Arithmetic Engine Blaise Pascal, a French mathematician invented the arithmetic engine. The arithmetic engine is the first successful mechanical calculator, which can add and subtract numbers containing up to eight digits. Its drawback was that it could not be produced by the technology at that time.
Page3 1670 Stepped Reckoner Gottfried Wilhelm von Leibnitz invented a calculator which can multiply and divide directly, as well as extract square roots. He called it the stepped reckoner. 1800 Jacquards Loom Joseph Marie Jacquard was the first to successfully use punch cards both storing information and for controlling the machine. He called it Jacquards Loom and became a successful milestone in textile industry and data processing. 1822 Difference Engine Analytical Engine First female computer programmer An English inventor and mathematician, Charles Babbage, invented thee difference engine. It is a calculator which compiles accurate navigational artillery tables. Babbage also conceived analytical engine in 1835. The machine has two basic components: memory and mill. The memory or storage unit holds possible numeric variables and results of all previous calculations. The mill processes data fed to it. The machine has the capacity to compare quantities and then decide what sequence of instructions to follow. The result of processing in the mill permits changing of already-stored value. Hence, it has the ability to modify its own program. He described in detail what might have been the worlds first working programmable computer. The analytic engine has never been built because it could not be produced by the technology during that time. The assistant of Charles Babbage who helped him in the machine design of his analytic engine was the daughter of the English poet Lord Byron and the Countess of Lovelace, Lady Augusta Ada King. Her understanding of the machine enabled her to create instruction routines that could be fed into the computer. This made her the first female computer programmer. In the 1980s, the U.S. Defense Department named a programming language, ADA in her honor. 1827 Boolean Algebra George Boole developed the algebra of logic, which expresses and processes problems in logic by using variables. These variables could only take the value of true or false. The Boolean Algebra, as it was called, became the perfect tool for designing the logic circuits of computers. 1884 Punched Card Tabulating Machine Dr. Herman Hollerith invented the automatic punched card tabulating machine in 1884 and the patent was issued in 1889. He then constructed an electromechanical machine using perforated cards for use in the first computerized U.S. census in 1890. Herman Holleriths machine was the first commercially successful data processing machine. 1944 Mark I Howard Aiken of the Harvard University, in collaboration with the IBM engineers, constructed Mark I. The official name of Mark I was Automatic Sequence Controlled Calculator. It took five years to build the size approximately 50 feet long, 8 feet high, with
Page4 7,000,000 moving parts and hundreds of miles of wiring. Mark I could perform the four basic arithmetic operations, locate stored information and process numbers up to 23 digits long. It could also multiply three eight-digit numbers in one second. It is considered the largest electromechanical computer and the first automatic general purpose digital computer. 1945 1st Computer Bug Dr. Grace Murray Hopper, a rear admiral in the United States Navy, was known for her discovery of the first computer bug in the Harvard Mark II computer. She found a moth on the wires of the computer causing it to malfunction, hence, the term bug and debugging originated. The moth or the bug now resides in the National Museum of American History in Washington D.C. 1946 ENIAC EDVAC John Mauchly and J. Presper Eckert from the University of Pennsylvania built the Electronic Numerical Integrator and Calculator (ENIAC). It was the first general-purpose electronic computer. The speed of calculation is a thousand times faster than the best mechanical calculator. It has 20 accumulators, wherein each one could perform 5,000 additions of ten-digit numbers in one second. Its limitation is that, it could only store 20 ten-digit numbers in memory at any given time. An improvement of the ENIAC led in the development of Electronic Discrete Variable Automatic Computer (EDVAC). It only used 30% of the vacuum tubes in ENIAC and was much faster in speed. It was designed by John von Neumann with the help of Mauchly and Eckert. The EDVAC was considered the first stored program computer. One of the major points of this von Neumann architecture was the use of a central processing unit, which controls and coordinates all computer functions. 1951 UNIVAC The first commercial computer, Universal Automatic Computer (UNIVAC), was designed by John Mauchly and Presper Eckert. It was successful in replacing the IBM punched card equipment at the U.S. Bureau of Census using magnetic tape as a buffer memory. 1975 BASIC Bill Gates and Paul Allen from Harvard wrote the first programming language for the Altair, which was cal