Memory management in an operating system Memory management in an operating system, which is also called as main memory management, because the main memory has central status for operations in present computer systems. Main memory comprises a large array of words or bytes which are from hundreds to thousands of millions in size. Every word and byte has its own memory address. Primary memory is basically a repository for quickly accessible data which is shared by CPU and I/O devices. During the instructions fetch cycle and both reads and writes data from the main memory the central processor reads instructions…
Author: jyoti gupta
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Horn clauses and satisfiability Horn formulas are conjunctions of Horn clauses. Horn clauses are an implication whose assumption (left side of the arrow) A is a conjunction of the proposition of type P and whose conclusion (right side of the arrow) is of type P (P::= ┴ | ┬| atom) also. Here is shown a Horn formula, having conjunctions of Horn clauses. H = (p → q)∧ (t∧ r → ┬) ∧ (p ∧ r ∧ s → ┴) A Horn formula is a formula φ of propositional logic if it can be generated as an instance of H in this…
Spiral model The Barry Boehm was mentioning the spiral model in his paper of 1986. In the spiral model, each phase has been beginning with goal design and ends with the customer or client progress reviewing. The spiral model is an important component of the SDLC models and that should also provide risk handling. In software engineering, the spiral model is the combination of the iterative and waterfall model and this model is used for the large project. The model contains many of the loops and each loop has also called the phase of the software development process. The software…
Conjunctive normal form A literal L is either an atom p or the negation of an atom ¬p. If a formula is a conjunction of clauses, where each clause D is a disjunction of literals then it is in conjunctive normal form (CNF), shown as C. L ::= p | ¬p D ::= L | L ∨ D C ::= D | D ∧ C. In Boolean logic, a formula is in conjunctive normal form (CNF) or clausal normal form if it is a conjunction of one or more clauses, where each clause is a disjunction of literals; it can also be described as…
The logic of soundness and completeness The logic of soundness and completeness is to check whether a formula φ is valid or not. To prove a given formula φ, there are two methods in logic. One is the syntactic method and the other semantic method. Syntactic method (⊢ φ): Prove the validity of formula φ through natural deduction rules or proof system. Semantic method (⊨φ): Prove the validity of formula φ through the truth table. Soundness Soundness is the property of only being able to prove things “true” or if the system (claims to) prove something is true then it is true.…
Operator precedence and associativity Operator precedence and associativity show the order or sequence in which operators are used. For example, you have below expression of operators: 4 + 3 * 5 > 4 * (3 + 1) – 5 Find its value? Find its execution sequence or order of the operators? According to math laws, parentheses expression is evaluated or executed first. (Nested parentheses can be used, in this situation inner parentheses expression execute first). When an expression used without parentheses, then the precedence rules and the associativity rules are applied according to the operator’s order. Precedence In operators, precedence…
Continue and break Statement ‘continue’ Statement The continue statement is used in the body of the loop. It is used to move the control to the start of the loop body. When this statement is executed in the loop body, the remaining Statements of the current iteration are not executed. The control directly moves to the next iteration. Example int x; for(z = 1; x<=5; x++) { cout<<”Hello zoetropefilm \n”; continue; cout<<”Knowledge is power”; } Explanation The above example has two court statements. One statement is before the continue statement and one is after continuing statement. The second statement is…
Loops in C++ Loops in C: A type of control structure that repeats statements or set of statements is known as a looping structure. It is also known as iterative or repetitive structures. In a sequential structure, all statements are executed once. On the other hand, conditional structures may execute or skip a statement based on some given condition. In some situations, it is required to repeat a statement or number of statements for a specified number of times. Looping structures are used for this purpose. There are different types of loops available in C++. while loop do-while and for…
SDLC – Software Development Life Cycle SDLC: Software development life cycle which used to produce the better quality of the system they should meet the requirement of the user or customer’s expectations and reach the completion time and estimates. The software development life cycle is a process that is used in industrial software to design and test high-quality software. It is also called the software development process. It is a framework that defines each step of the task that is performed in the software development life cycle. Definition of SDLC: The software development life cycle is consists of a detailed…
Silicon and Germanium In fig the atomic structure of Silicon and Germanium are given we compared the atomic structures of Silicon and Germanium to each other. Silicon is used in semiconductor devices, diodes and integrated circuits. Both have four valence electrons. It is often say that it have valence electron in the 3rd shell and in the germanium the four valence electrons are in 4th shell. This shows that the silicons has less energy level and germanium has high energy level an extra additional energy is required to escape from the atom. At high temperature it makes the germanium more…
Operating System Functions There are basic functionalities of operating system functions are given as Booting Memory management Loading and execution Data security Disk management Device management Process management Coordination between other software and users Control over system performance Job accounting Error detecting aids Printing Control Booting The starting process of computer is called as booting it make computer to start work. It checks the availability of required resources and software for making computer ready to work. Memory Management Operating system manage main memory. Main or primary memory is fast storage which can access directly by CPU, so program must…
Operating System Overview Operating system is basically a program which is used to manage the computer hardware.it behaves as a midway between computer hardware and computer user and also provides basis for application programs. Main objective of operating system is to provide a well-organized and convenient environment for user in which they can execute the programs. Because of its complexity and massiveness, it must be created piece vise. Each and every piece of this program should be a well-defined part of the system with carefully defined input, output and functions. Operating systems has some amazing aspects about how varied they…
Propositional logic- formal language Propositional Logic (PL) is a formal language, which has syntax, a set of symbols, and semantics. It is not a natural language such as English. All languages have a set of symbols, meanings assigned to the significant units and rules for constructing compound constructions out of atomic constructions. For example, the letter ‘Z’ is part of English, but not part of Hindi. For example, ‘snow’ means snow in English, but ‘Schnee’ means snow in the German language. For example, English is a Subject-Verb-Object language, while Arabic is Subject-Object-Verb. The syntax of a language is known as…
Semiconductors, Conductors, Insulators and Band Gap Semiconductors The semiconductor are those type of material that are between in conductors and insulators and it have ability to conduct the electrical current. The semiconductors are not good conductors neither good insulators they are in pure state. Antimony, arsenic, boron and polonium are the single element semiconductors. And most commonly used compound semiconductors are gallium, carbide, nitride and germanium. The mostly commonly used semiconductor is Silicon. Conductors The conductors are those type of material that allow the flow of charge are called conductors. The most common examples of conductor are aluminum, gold, silver…
Electronics introduction Electronics is the science that deals with electrical devices and circuits that operate by controlling the flow of electrons and other charge particles. This branch of science deals how electrons behave in gases, vacuum or semiconductors. Basic Components of Electronic The basic components that frequently used in electronic are Resisters Capacitors Inductors Transistors Diodes etc. This is not complete list of components there are many components that belong to the electronic but these are the basic components of electronic that commonly used in electronic. Using these basic components it is possible to create more useful and complex…
Five Patterns The software architecture patterns have including the five patterns with details and they should be given below… 1. Layered Pattern: The layered patterns are one of the most well define software architecture patterns. The various developer is used and without know the name. However, each layer has its owns responsibility and provide high layer services. There are not predefine the number of layers. Presentation layer Business Layer Application layer Data access layer Database layer The user initiates some piece of the code in the presentation layer that has been performing some action.so the presentation then called the underlying…
Natural deduction Natural deduction System for a structured deduction from a set of assumptions, based on rules, specific to the logical connectives. The way of proving that an argument is valid is to break it down into several steps and to show that everyone can conclude some more obvious and valid arguments. The proof system is defined in purely syntactic terms. A deduction is a sequence of formulas formed by obeying some fixed rules. For proving theorems in mathematics or any other science, deduction is a simplified model. Deductions are also called formal proofs. If a deduction is correct, it…
Java loops A type of control structure that repeats a statement or set of statements is known as loops. In Java programming language there are three basic iteration statements which are for, while and do-while. These three statements generally called loops. A loop repeatedly executes the same procedures which write into the loop body until a termination condition is met. A loop used when a programmer needs to execute a large iteration process, and he wants to save your time writing one code repeatedly. Every programming language has loops concepts, without this concept languages are not efficient for programmer persons.…
If else Statement C++ Control Structure A statement used to control the flow of execution in a program is called a control structure. The instructions in a program can be organized into three kinds of control structures to control execution flow. The control structures are used to implement the program logic. and the if-else statement following. Types of Control Structures Different types of control structures are as follows: Sequence In a sequential structure, the statements are executed in the same order in which they are specified in the program. The control flows from one statements to another in a logical…
Input and output in C++ Input and output in c++! The process of going something to the computer is known as input. The input is mostly given by the keyboard. Programs may need certain inputs from the users for working properly. The term standard input refers to the input via the keyboard. input and output defined in the following. The process of getting something from the computer is known as output. The output is mostly displayed on the monitor. The terms standard output refers to the output display on the monitors. The result of the program is the output of…