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Operating System

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1. Explain the concept of Re-entrancy. It is a useful, memory-saving technique for multiprocessing time sharing systems. A Re-entrant Procedure is one in which multiple users can share a single copy of a program during the same period. Re-entrancy has 2 key aspects: The program code cannot modify itself, and the local data for each user process must be stored separately. Thus, the permanent part is the code, and the temporary part is the pointer back to the calling program and local variables used by that program. Each execution instance is called activation. It executes the code in the permanent part, but has its own copy of local variables/parameters. The temporary part associated with each activation is the activation record. Generally, the activation record is kept on the stack. Note: A re entrant procedure can be interrupted and called by an interrupting program, and still execute correctly on returning to the procedure. 2. Explain B...
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Computer Networks

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1. What are the two types of transmission technology available? (i) Broadcast and (ii) point-to-point 2. What is subnet? A generic term for section of a large networks usually separated by a bridge or router. 3. Difference between the communication and transmission. Transmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc. Communication means the meaning full exchange of information between two communication media. 4. What are the possible ways of data exchange? (i) Simplex (ii) Half-duplex (iii) Full-duplex. 5. What is SAP? Series of interface points that allow other computers to communicate with the other layers of network protocol stack. 6. What do you meant by "triple X" in Networks? The function of PAD (Packet Assembler Dis-assembler  is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another ...
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SQL

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1. Which is the subset of SQL commands used to manipulate Oracle Database structures, including tables? Data Definition Language (DDL) 2. What operator performs pattern matching? LIKE operator 3. What operator tests column for the absence of data? IS NULL operator 4. Which command executes the contents of a specified file? START or @ 5. What is the parameter substitution symbol used with INSERT INTO command? & (amp;) 6. Which command displays the SQL command in the SQL buffer, and then executes it? RUN 7. What are the wildcards used for pattern matching? _ (under score) for single character substitution and % for multi-character substitution 8. State true or false. EXISTS, SOME, ANY are operators in SQL. True 9. State true or false. !=, < >, ^= all denote the same operation. True 10. What are the privileges that can be granted on a table by a user to others? Insert, update, delete, selec...
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RDBMS

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1. What is database? A database is a logically coherent collection of data with some inherent meaning, representing some aspect of real world and which is designed, built and populated with data for a specific purpose. 2. What is DBMS? It is a collection of programs that enables user to create and maintain a database. In other words it is general-purpose software that provides the users with the processes of defining, constructing and manipulating the database for various applications. 3. What is a Database system? The database and DBMS software together is called as Database system. 4. Advantages of DBMS?Ø Redundancy is controlled. Ø Unauthorised access is restricted. Ø Providing multiple user interfaces. Ø Enforcing integrity constraints. Ø Providing backup and recovery. 5. Disadvantage in File Processing System?Ø Data redundancy & inconsistency. Ø Difficult in accessing data. Ø Data isolation. Ø Data integrity. Ø Co...
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