Computer Engineering

 . Operating System An operating system is a collection of software program that controls the overall operation of the computer system. The Operating System manages the resources of a computer system manages the resources of  computer system and schedules its operation. The operating system acts as an interface between the hardware and the user level program and facilitates the execution of the program.    Function of Operating System 1. File Management :  Operating system handles the file organizations in the secondary storage devices. Operating system also provides certain services to the computer system in one form or the other. The operating system provides certain services to the users which can be listed in the following manner.  Program Execution  Error Detection and Handling Manipulation of File System Information and Resource Protection Handling Input/Output Operations Accounting 2. Security : The operating system uses password protection to protect user data and similar othe

 . Boolean algebra consists of two binary operations + and., unary operation, two distinct element 0 and 1, and variables that holds 0 and 1. Following are different laws of Boolean algebra. Lets a,b,c be Boolean variables then 1. Identity Laws  a) a + 0 = a                                        b) a.1 = a 2. Complement Laws a) a + a' = 1                                        b) a.a' = 0 3. Idempotent Laws a) a + a = a                                        b) a.a = a 4. Boundedness Laws  a) a + 1 = 1                                        b) a.0 = 0 5. Absorption Laws  a) a + (a.b) = a                            b) a.(a + b) = a 6. Commutative Laws  a) a + b = b + a                                   b) a.b = b.a 7. Associative Laws  a) (a + b) + c = a + (b + c)               b) (a.b).c     = a.(b.c) 8. Distributive Laws a) a + (b.c) = (a + b). (a + c)           b) a.(b + c) = (a.b) + (a.c) 9. Involution Law     (a')' = a 10. De-Morgan's Laws a) (a + b)' = a&#

 . Boolean Algebra Boolean Algebra is used to analyze and simplify the digital ( logic) circuits. Boolean algebra sometimes referred to as the algebra of logic, is a two valued system of algebra that represents logical relationships and operations. English logician and mathematician George Boole, the first to apply these algebraic techniques to the logic process, contended that any statement (any declarative sentence that is either true or false but not both) could be assigned a binary value, such as "true/false" or "yes/no" or "on/off" of "0/1". In 1854, Boole wrote An Investigation of the Laws of Thought, in which he discussed ways of reducing logical relationships to simple statements of equality, inequality, inclusion and exclusion. Boole then showed ways to express these statements symbolically, using binary ( two-valued) code, and created algebraic rules that governed these logical relationships. Truth Table Function A truth table represent

 . Number  is a way to represent or express the numbers in a computer system which is known as the number system. Number system plays a great role in computing and electronics. Before numbers, people used stones and sticks for the purpose of counting. Decimal system was discovered by great Hindu philosophers, since then man are using it as their daily need. In our day to day activities we use decimal number system which uses symbols 0,1,2,3,4,5,6,7,8 and 9 to represent digits. However, computers only understand binary numbers which uses symbols 0 and 1 to represent the digit.  Decimal Number System The Decimal Number System has the base number 10 and this notation is called the decimal notation. This number system has its applications in computer and computer science. The decimal number are written with subscript 10 as (4532) 10   or with suffix D as 3642D. For example :  (56425) 10 or (56425) D Binary Number System Binary number system is used by computers and digital electronic devi

. Measurement of unit of processing speed : Units Equivalent 0 or 1 1 Bit 4 Bites 1 Nibble 8 Bites 1 Byte 1024 Bytes 1 Kilobyte(KB) 1024 Kilobytes 1 Megabyte(MB) 1024 Megabytes 1 Gigabyte(GB) 1024 Gigabytes 1 Terabyte(TB) 1024 Terabytes 1 Petabyte(PB) 1024 Petabytes 1 Exabyte(EB)   Storage Unit :    The devices which is used to store any data temporary or permanently are called storage device or storage unit. Storage devices are two types : 1. Primary Storage Devices :  Read more 2. Secondary Storage Devices   Read more Home

 . Input Device The device which is used to input data of input are called input devices. The data input to a computer can be in the form of text, audio, video etc.  Types of Input devices which are given bellow : 1. Keyboard :  Keyboard is input device which is used for entering text latter or character to the computer. Standard keyboard contains 101 keys which are arranged in the same order as a typewriter. 2. Mouse : Mouse is a pointing device which is used to position cursor on screen, move an object by dragging or select an object by clicking. Mouse is am small hand held device having two button on its upper side and small wheel between the buttons. 3. Joystick :   Joystick is a device which is commonly used for playing video games. Joystick is mainly used to control the speed of the cursor and is thus popular in games involving speed like racing and flying games. 4. Digitizing Tablet : Digitizing Tablet is an input device used primarily to input drawing, sketches etc. It is used

 . Primary Memory Primary memory is the main memory of computer. It is used to store data and instructions during the processing of data. Primary memory is semiconductor memory. Primary memory is of two kinds Random Access Memory (RAM) and Read Only Memory (ROM). RAM is volatile. It stores data when the computer is on. The information stored in RAM gets erased when the computer is turned off. RAM provides temporary storage of data and instructions. ROM is non-volatile memory, but it is a read only memory. The storage in ROM is permanent in nature and is used storing standard processing programs that permanently reside in the computer. ROM comes programmed by the manufacturer. RAM stores data and instructions during the execution of instructions. The data and instructions that require processing are brought into the RAM from the storage devices like hard disk. CPU accesses the data and the instructions from RAM, as it can access it at a fast speed than the storage devices connected to t

 . Mobile Computing : Mobile Computing is a technology which allows for the transmission of data, voice and video. Mobile computing involves mobile communication, mobile hardware and mobile software.  The concept of Mobile Computing can be divided into three parts : Mobile communication Mobile hardware Mobile software Mobile Communication  Mobile Communication is a specifies framework that is refers to the infrastructure put in place to ensure that seamless and reliable communication goes on. These would include devices such as protocols, services, bandwidth and portals necessary to facilitate and support the stated services. The data format is also defined at this stage. It does not depend on a physical connection between the sender and receiver. Mobile Hardware  Mobile hardware includes mobile devices or device components that receive or access the service of mobility. These devices are configured to operate in full-duplex, whereby they are capable of sending and receiving signals at

 . There are four types of computer based on size. They are given bellow: 1. Super computer : A computer that is capable to working at very high speed and can process a very large amount of data with in an acceptable time. It processes the data and instructions in millionths of a second, or microseconds. The first super computers were introduced in the 1960s, designed primarily by Seymour Cray at Control Data Corporation (CDC).    Super computer are used for highly calculation-intensive task such as weather forecasting, climate research, molecular, modeling, physical simulations such as simulation of airplanes and other scientific and engineering research. 2. Mainframe Computer : Mainframe computers are large computers which process at high speed and occupies large space. A centrally located CPU is connected with more than 100 terminals. Example of these computers are : IBM 1401, ICL 2950/10 etc. Some of the major characteristics of these computers are listed below : Very large in size

 . History of computer starts from that time when there were not any number systems discovered and there were no device for calculation. When men faced problems, newer and newer devices were developed, which are described as followings:  1. Age of Mechanical Calculators : a) Abacus :  It was the earliest counting device. As show in the figure, it had two parts called heaven and earth. It could only add and subtract. It is believed to be discovered in China, Russia or Egypt. b) John Napier and his rods : Scottish mathematician John Napier invented a principle of calculation called logarithm in 1614 AD and based on the same principle he invented some bone rods engraved with numbers in 1617 AD, which was called Napier's Bone. With the help of this device, people could do multiplication very faster. c) William Aughterd and his Slide Rule : English mathematician William Augtherd discovered a device with two rulers fro calculation, which was based on Jhon Napier's principle but used

 . DBA Administer : DBA is a person or group who has central over both data and application. DBA very depending upon the job disruption and policy of organization. Some of the responsibility of database administer are as following : 1. Schema : Definition and modification : The overall structure of database is called database schema. It is the responsibility of to create Database schema and modified it. 2. New software installation : It is the responsibility of DBA to install new DBMS software other application software as per organizational need.  3. Security enforcement and Administration :   DBA is responsible for establishing and meatotomy the security of Database. 4. Data analysist : DBA is responsible for analyst the data store in the database. 5. Database designed : DBA works along with the development team during the database designed due to which problems that can a rise can be avoided.  6. Routing maintenance check : The DBA is responsible for taking database backup parodical

 . Introduction Of DML It is defined as the language that provides set of operations to support the basic data manipulation operations on the data held in the database. It allows user to insert, update, delete, and retrieve data from the database. The data manipulation is : The retrieval of information stored in database  The insertion of new information into the database. The deletion of information from the database The modification of information stored in database The part of the DML that involves the data retrieval is called a query language. Following are the commands used in DML SELECT : retrieves data from database   INSERT : insert data into table UPDATE : update existing data with a table  DELETE : delete all records from a database table MERGE : UPSERT operation (insert or update) CALL : call a PL/SQL or java subprogram EXPLAINPLAN : interpretation of the data access path LOCKTABLE : concurrency table

 . Database Language : Language that are used to interact with the database management system are called database language. These database language are used to create and maintain database on computer. There are large number of database language such as dBase, MS-Access, Foxpro, Oracle, MYSQL, Sybase, Paradox. etc. There are two types of languages :   1. Data Definition Language/ Data Description Language (DDL) 2. Data Manipulation Language (DML)

.  Introduction of DDL : It is a language that allows the users to define data and their relationship to other types of data. DDL is the short form of Data Definition Language, which deals with database schema and description of how the data should reside in the database. It is mainly used to create files, database, data dictionary and table within database. DDL can be used to define the conceptual/ Global/ Logical schema. A DDL is a language used to define data structures and modify data. Following are the commands of DDL :  CREATE : It is used to create object in the database. The CREATE command can be used to establish each of these database on your platform. ALTER : It alters the structure of the database. The ALTER command allows you to make changes to the structure of a table without deleting and recreating it. Drop : Delete object from the database. The final command of the Data Definition Language, DROP, allows us to remove entire database objects from our DBMS. For example DRO

. Database : A database is a collection of  related data organized in a way that data can be easily accessed, managed and updated. Database is actually a place where related piece of information is stored and various operations can be performed on it.  Database constitute the most important component of any computer based information system. A database may be defined as a collection of inter related relevant data stored together to server multiple application. Feature of Database : Share : Data in a database is sharing among different user and application. Validity : Data should be correct with respect to the real word entity that they represent. Security : Data should be protected from unauthorized user access. Non redundancy : No two data items in a database should represent the same real word entity. Consistency : Data in a database should be some for all users.  Database Management System (DBMS) : Database Management System (DBMS) is a collection of interrelated data and a set of p