Apps1 - Part 1

8/6/2019 Apps1 - Part 1

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System Software

The Computer Defined

• A computer is an electronic device that processes data, converting it into information that isuseful to people . Any computer-regardless of its type-is controlled by programmed

instructions, which give the machine a purpose and tell it what to do.

Digital and Analog Computers

Digital computers are so called because they work 'by the numbers." That is, they break alltypes of information into tiny units, and use numbers to represent those pieces of information.

• Digital computers also work in very strict sequences of steps, processing each unit of information individually, according to the highly organized instructions they mustfollow.

A lesser-known type of computer is the analog computer, which works in a very different wayfrom digital computers.

• The earliest computers were analog systems, and today's digital systems, owe a greatdeal to their analog ancestors.

• Analog and digital computers differ in many respects, but the most importantdistinction is the way they represent data.

Digital systems represent data as having one distinct value or another, with no otherpossibilities.

Analog systems, however, represent data as variable points along a continuous spectrum of values.

This makes analog computers somewhat more flexible than digital ones, but notnecessarily more precise or reliable.Early analog computers were mechanical, weighing several tons and using motors andgears to perform calculations

Computers can be categorized in several ways.Some computers are designed for use by one personSome are meant to be used by groups of peopleSome are not used by people at all.

They also can be categorized by their power, which means the speed at which theyoperate and the types of tasks they can handle.Within a single category, computers may be subcategorized by price, the types of hardware they contain, the kinds of software they can run, and so on.

Computers for Individual Users

Most computers are meant to be used by only one person at a time. Such computer, are oftenshared by several people such as those in your school's computer lab), but only one user can workwith the machine at any given moment. The six primary types of computers in this category are:

Desktop computersWorkstationsNotebook computer,

Tablet computers

Percival A FernandezSystem Software

8/6/2019 Apps1 - Part 1


8/6/2019 Apps1 - Part 1


considered as an example of computer processing. With the ability of data manipulation of company, task can be completed efficiently with effectively. Saving lots and lots of time andeffort, compared to human work.

StorageImagine you have a collections of ten thousand photos. With the advent of computer, you can justsave that ten thousand photos and bring your laptop over. That’s that simple!. Example of

computer storage include, harddisk, cd rom, dvd rom and others.OutputOutput is one of the most commonly used function in computer. It may refers to the graph that isbeing plotted in microsoft excel, the song that you are playing from media player, the powerpointslide, so if anyone ask you, what is the basic functions of computer, always remember the belowstory.

Memory Devices

In a computer, memory is one or more sets of chips that store data and/or program instructions,either temporarily or permanently. Memory is a critical processing component in any computer.

Personal computers use several different types of memory, but the two most important are calledrandom access memory (RAM) and read-only memory (ROM).

These two types of memory work in very different ways and perform distinct functions.

Random Access Memory

The most common type of memory is called random access memory ( RAM). As a result, the termmemory is typically used to mean RAM. RAM holds data and program instructions while the CPUworks with them. When a program is launched, it is loaded into and run from memory. As theprogram needs data, it is loaded into memory for fast access. As new data is entered into thecomputer, it is also stored in memory-but only temporarily.

RAM is volatile, meaning that it loses its contents when the computer is shut off or if there is apower failure . Therefore, RAM needs a constant supply of power to hold its data. For this reason,you should save your data files to a storage device frequently, to avoid losing them in a powerfailure.

The most common measurement unit for describing a computer's memory is the by the amount of memory it takes to store a single character, such as a letter of the alphabet or a numeral. Whenreferring to a computer's memory, the numbers are often so large that it is helpful to use termssuch as kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB) to describe the values

Read-Only Memory

Unlike RAM, read-only memory ROM, permanently stores its data, even when the computer is shut

off. ROM is called non-volatile memory because it never loses its contents. ROM holds instructionsthat the computer needs to operate. Whenever the computer's power is turned on, it checks ROMfor directions that help it start up, and for information about its hardware devices.

Characteristics of Computers

1. Speed : The computer present in the modern world has the speed of nano and pico second. The various speed that are used by the computers from the former generations are as follows:


8/6/2019 Apps1 - Part 1


1 milli second=1*10^-3 second1 micro second=1*10^-6 second1 nano second=1*10^-9 second1 pico second=1*10^-12 second

2. Accuracy: The accuracy of computers is quite high. They are reliable and robust. It ever makesa mistake. Most probably the error occurs due to the user rather than the computer. There may becertain hardware mistake but with the advanced technique in hand they are overcome.Example: Only accurate robots are used to perform the operations for the patients since humanhands are not flexible for making operations.

3. Diligence: Unlike human beings, computers are persistent and are not afflicted by tiredness,monotony, lack of concentration, etc.If there are surplus amount of executions to be made then each and every execution will beexecuted at the same time period. They can perform their assigned task without taking anyrefreshment.Example: Computers which are used for controlling the satellites.

4. Reliability: Computers produce reliable and precise results. Humans cannot work with suchprecision. The computers are automatic. It may execute the process without any intervention of user once they are assigned to a work. Once the data or instruction are fetched from thesecondary devices such as optical disks, hard disks etc. Immediately they get stored into RAM(primary memory) and then sequentially they get executed.

5. Versatility: Computers can work with different types of data like sound, graphics, audio, etc.In our day to day life computers has been a part, with their extended flexibility they are used, allover the world. They can be used as personal computers, for home uses, for business orientedtasks, weather forecasting, space explorations, teaching, railways, banking, medicine etc. AllModern computer can perform different kind of tasks simultaneously.

6. Memory: Computers can store large amounts of data for years till a hardware failure occurs.Secondary storage devices are the key for the data storage. They store the data for which theuser wants to retrieve these data for future use. The examples for various secondary devices areFloppy disk, Optical disks (CS and DVD), Zip drives, Thumb drives etc. The data of smaller size canbe easily fetched and they can be copied to the primary memory (RAM).

History and Generations of ComputersAlthough the computer is a 20th-century invention, its predecessors reach as far back as the 17thcentury. Computers have undergone four generations of development, with the first computers of the 1940s launching the first generation. Each generation of computer has become smaller, moreversatile and more powerful. The most recent generation resulted in the rise of the personalcomputer, ushering in the information age.

Precursors

Historians of science see the abacus, first invented in Babylon in the 300s B.C.E., as a predecessorof the computer . In the modern era, William Schickland designed a mechanical calculator in 1623,a design which Blaine Pascal improved two decades later . Charles Babbage in England came upwith the concept of a steam-powered calculating machine (the analytical machine) in the mid-1800s , but he failed to convince the British government to finance the project.

The First Electronic Computer

The British government built an electronic computing device during World War II (1939-1945 inEngland) to break the German's Enigma code . It was called Colossus, and the Americans followedthe British with a computer a few years later, known as the Electronic Numerical Integrator And


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Computer (ENIAC). The ENIAC is generally considered the first electronic computer because of theColossus's limited computational ability. Scientists at the Ballistics Research Laboratory and theUniversity of Pennsylvania designed and built the ENIAC on commission from the U.S. army tohelp formulate ballistics data for use in bombings and artillery.

Generations

The ENIAC represents the first generation of computers. Vacuum tubes composed the circuitry of

computers like ENIAC; input to the computers was in the form of a punch card or magnetic tape,and output was in the form of print-outs. The invention of the transistor, which was a muchsmaller form of circuitry that used less power, ushered in the second generation of computersduring the 1950s. The second generation of computers used programming languages likeFORTRAN and COBOL, although the operating system had not yet been developed.

Development of the Operating System

In the mid-1960s, the integrated circuit replaced the transistor, which led, once again, to smallerand more powerful computers. During this third generation of computers, programmers developedmore computer languages, like BASIC, C and Pascal. IBM OS/360 and UNIX debuted as the firstoperating systems. The development of the operating system, which standardized computeroperations, led to the growth of commercial applications.

Information Age The microprocessor inaugurated the fourth generation of computers. The integrated circuit hadminiaturized the circuitry of a computer, but the microprocessor was a small chip that containedall of the basic functions of a computer (processing, memory and input/output). Intel introducedthe first microprocessor in 1980--the Intel 4004. The reduction of size made possible by themicroprocessor permitted the building of smaller computers, leading directly to the personalcomputer that dominates today as well as the Information Age.


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