NEB Class 11 · Past paper
The complete NEB Class 11 2072 exam paper for Computer Science, all 15 questions with solved model answers.
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Describe any five logic gates with Truth Table and gate symbol. [10]
A logic gate is a basic digital circuit that produces a single binary output from one or more binary inputs according to a logical rule. Five common gates are described below. 1. AND gate - output $1$ only when all inputs are $1$.
What are the primary objectives of operating system? Describe any four functions of operating system. [2+8]
Primary objectives of an operating system:
Four functions of an operating system:
1. Process management - it creates, schedules and terminates processes, allocates CPU time among them and handles their synchronisation so that many programs can run smoothly.
2. Memory management - it keeps track of main memory, decides which process gets memory and how much, allocates and de-allocates memory, and manages virtual memory.
3. File management - it organises data into files and folders, and controls creating, opening, reading, writing, saving and deleting of files along with access permissions.
4. Device (I/O) management - it controls all input and output devices through device drivers, manages buffers and queues, and coordinates data transfer between devices and the CPU.
(Other functions include security and protection, user interface and error handling.)
Define the terms 'computer architecture' and 'computer organization'. Explain the different units of computer system with suitable block diagram. [2+8]
Computer architecture is the design of a computer system as seen by the programmer, including the instruction set, data types, addressing modes and registers (the logical, functional view of what the computer does). Computer organization deals with how the architecture is implemented in hardware, such as the control signals, interconnections and memory technology (the physical view of how it works).
Units of a computer system (block diagram):
+-------------+ +----------------+ +-------------+
Input ->| Input Unit | ----> | CPU | ----> | Output Unit | -> Output
+-------------+ | (ALU + CU + | +-------------+
| Registers) |
+-------+--------+
|
+-----v------+
| Memory Unit|
+------------+
The arrows show the flow of data (solid) and control signals from the CPU to all units.
What is programming language? Explain the different programming language with their major features. [2+8]
A programming language is a set of symbols, words and rules (syntax) used to write instructions (programs) that a computer can execute to perform tasks. Different programming languages and their features: 1. Machine level language - writ...
Describe the fourth generation of computer. [5]
Fourth generation computers (1971 onwards) use the microprocessor, a single silicon chip that contains the whole CPU, built with VLSI (Very Large Scale Integration) technology. Main characteristics: - Technology: microprocessor (LSI/VLSI...
What is octal number? Convert (167)8 octal number into (?)16 hexadecimal number. [1+4]
An octal number is a number expressed in the base $8$ system, which uses the digits $0$ to $7$.
Convert $(167)_8$ to hexadecimal: first convert each octal digit to 3 bit binary, then regroup into 4 bit groups for hexadecimal.
$$ \begin{aligned} 1 &= 001 \ \quad 6 &= 110 \ \quad 7 &= 111 \ (167)_8 &= (001,110,111)_2 \ &= (001110111)_2 \end{aligned} $$
Group the binary in fours from the right: $$ \begin{aligned} \underbrace{0111}{7}\ \underbrace{0111}{7} \ (167)8 &= (77){16} \end{aligned} $$
Check:
$$ \begin{aligned} (167)8 &= 1\times64 + 6\times8 + 7 \ &= 119{10} \end{aligned} $$
and
$$ \begin{aligned} (77){16} &= 7\times16 + 7 \ &= 119{10} \end{aligned} $$
Verified.
What is memory? List out any four differences between primary and secondary memory. [1+4]
Memory is the storage part of a computer that holds data, instructions and results temporarily or permanently. Four differences between primary and secondary memory: Primary memory Secondary memory ------ Directly accessed by the CPU Not...
What is program testing and debugging? Explain why logical errors are difficult to find and correct than syntax errors. [1+4]
Program testing is the process of running a program with sample data to check whether it produces correct results and to find errors. Debugging is the process of locating and removing (fixing) the errors (bugs) found during testing. Why ...
What is word processor? Give the major features of word processor. [1+4] OR List the advantages and disadvantages of Internet. [5]
A word processor is application software used to create, edit, format, save and print text based documents such as letters, reports and books. Example: MS-Word. Major features of a word processor: - Creating, editing, saving, opening and...
What is spreadsheet application program? List the uses of spreadsheet. [1+4]
A spreadsheet is application software that arranges data in a grid of rows and columns (cells) and lets the user enter, calculate, analyse and present numeric data using formulas and functions. Example: MS-Excel. Uses of a spreadsheet: -...
What is mobile computing? Explain why it is becoming more popular these days. [1+4] OR Differentiate between micro computer and super computer. [5]
Mobile computing is the technology that allows people to transmit data, voice and video and access information through portable wireless devices without being connected to a fixed physical link. Why it is becoming more popular: - Mobilit...
Describe the terms 'Operator', 'Operand' and 'Operation' with suitable examples. [5]
In programming, an expression is formed using operators and operands, and the task they perform is the operation. 1. Operand - the value, variable or constant on which an operation is performed. In the expression A + B, the operands are ...
What is HTML? Describe the importance of HTML in web-page designing. [1+4] OR What is Database Management System? List out the different application areas of Database Management System. [1+4]
HTML (HyperText Markup Language) is the standard markup language used to create and structure web pages using tags that a browser interprets to display content. Importance of HTML in web page designing: - It provides the basic structure ...
Subtract (100000)2 from (111)2 using 1's and 2's complement method of subtraction. [2.5+2.5]
We compute $(111)2 - (100000)2$. Since $(111)2 = 7$ and $(100000)2 = 32$, the result will be negative. Using 6 bit numbers, the minuend is $000111$. Using 1's complement method: 1's complement of $100000$ is $011111$. Add to the minuend:...
Write short notes on: (a) Cache Memory (b) Bus in the Computer System. [2.5+2.5]
a. Cache memory Cache memory is a small, very fast memory placed between the CPU and the main memory (RAM). It stores copies of the data and instructions that the CPU uses most frequently, so the processor can fetch them quickly instead ...
A logic gate is a basic digital circuit that produces a single binary output from one or more binary inputs according to a logical rule. Five common gates are described below. 1. AND gate - output only when all inputs are .
An octal number is a number expressed in the base system, which uses the digits to .
Convert to hexadecimal: first convert each octal digit to 3 bit binary, then regroup into 4 bit groups for hexadecimal.
Group the binary in fours from the right:
Check:
and
Verified.
We compute . Since and , the result will be negative. Using 6 bit numbers, the minuend is . Using 1's complement method: 1's complement of is . Add to the minuend:...