Computer Science
कम्प्युटर विज्ञान · Class 12 · Code 4281 (CDC Com.428)
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The syllabus asks for
- Introduction to data, database, database system, DBMS
- Field, Record, Objects, Primary Key, Alternate key, Candidate key
- Advantages of using DBMS
- DDL and DML
- Database Models: Network Model, Hierarchical Model, Relational database model
- Concept of Normalization: 1NF, 2NF, 3NF
- Centralized vs Distributed Database
- Database Security
Key points
- Data are raw facts; information is processed data. A database is shared, integrated data; a DBMS is the software managing it; a database system is hardware + software + data + users + procedures.
- The three-level architecture (external / conceptual / internal) plus its two mappings gives logical and physical data independence.
- Field = column = attribute; record = row = tuple. Degree = number of columns, cardinality = number of rows.
- Super key ⊃ candidate key; one candidate key becomes the primary key (unique, never NULL), the others are alternate keys; a foreign key matches a primary key in another table and gives referential integrity.
- DDL (CREATE, ALTER, DROP, TRUNCATE) defines structure; DML (SELECT, INSERT, UPDATE, DELETE) manipulates data; DCL (GRANT, REVOKE) controls access; TCL (COMMIT, ROLLBACK) controls transactions.
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The syllabus asks for
- Basic elements of Communication System
- Concept of Communication System; Block Diagram of communication model
- Elements of Data Communication/Transmission
- Simplex, Half duplex and Full duplex communication mode
- Concept of LAN and WAN
- Transmission Medium: Guided and Unguided
- Transmission impairments: Jitter, Singing, Echo, Crosstalk, Distortion, Noise, Bandwidth, Number of receivers
- Network Architecture: Client-Server and Peer-to-peer
- Basic Terms and Tools: IP Address, Subnet Mask, Gateway, MAC address, Internet, Intranet, Extranet
- Network Tool: Packet tracer, Remote Login
- Network Connecting Devices: NIC, Modem, Router, Switch
- Network Topologies: Bus, Ring and Star topology
- Basic Concept of OSI Reference Model
- Internet Protocol Addressing
Key points
- The five elements of data communication are message, sender, receiver, transmission medium and protocol; the communication model is source → transmitter → transmission system → receiver → destination, with noise added in the middle.
- Simplex = one direction; half duplex = both directions alternately; full duplex = both directions at once.
- LAN (a building, private, fastest) ⊂ MAN (a city) ⊂ WAN (country or world; the Internet is the largest WAN).
- Guided media (twisted pair, coaxial, fibre) confine the signal in a conductor; unguided media (radio, microwave, infrared, satellite) radiate it into space. Fibre has the highest bandwidth and immunity to interference.
- Impairments: attenuation, distortion, noise (thermal, intermodulation, crosstalk, impulse), echo, singing, jitter; bandwidth and the number of receivers limit what a channel can do.
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The syllabus asks for
- Introduction; Server side and Client Side Scripting
- Introduction of internet technology
- Adding JavaScript to HTML page; JavaScript fundamentals
- JavaScript Data types; Variables and operators
- Functions and control structures: if-else, if-else-if, switch-case, for, while, do while
- Object based programming with JavaScript and Event handling
- Image, event and form objects
- Form validation; JQuery
- Server Side Scripting using PHP; Hardware and Software Requirements
- Object oriented programming with server side scripting
- Basic PHP syntax; PHP data types; Basic Programming in PHP
- Operators: arithmetic, logical, comparison, operator precedence
- Variables Manipulation
- Database Connectivity; Connecting server side script to database
- Making SQL queries; Fetching data sets; getting data about data
- Creating SQL database with server side scripting; Displaying queries in tables
Key points
- Client-side scripts (JavaScript) run in the browser — fast, visible to the user, cannot touch a database. Server-side scripts (PHP) run on the web server — hidden, slower by one round trip, and the only way to reach a database.
- JavaScript is interpreted, case sensitive, loosely typed and object-based. It is added to a page inside <script> in the head or body, or linked from an external .js file.
- Data types: number, string, boolean, null, undefined (primitive) and object, array, function (non-primitive). == compares values only; === compares value and type.
- Control structures: if / else if / else, switch-case, for, while, do-while. do-while always executes its body at least once.
- Everything in the browser hangs off window: document, then forms[], images[], links[], then the individual fields. Events (onclick, onsubmit, onmouseover, onload) connect user actions to functions.
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The syllabus asks for
- Review of C programming concepts
- Functions: library and user defined functions and advantages
- Function definition, prototype, call and return statements
- Accessing a Function by passing values
- Storage classes: automatic and external
- Recursion: factorial and Fibonacci problems
- Structure: definition, declaration, initialization and size
- Accessing members of structure; Array of structure
- Union: definition, declaration; Difference between union and structure
- Pointers: definition; Address (&) and indirection (*) operator
- Pointer Expression and Assignment; Call by value and call by reference
- Working with Files: Concept of Data File; Sequential and Random File
- File manipulation functions: putw, getw, putc, getc, fscanf, fprintf
- Opening, Reading, Writing and Appending data file
Key points
- A C program is a set of functions; main() is the one that runs first. A function needs a prototype, a definition and a call, and return sends back exactly one value.
- Library functions come from headers (stdio.h, math.h, string.h); user-defined functions are written by the programmer. Functions give reusability, modularity, readability and easier debugging.
- Storage classes: auto (stack, garbage, block scope, dies with the block), extern (data segment, 0, whole program), static (data segment, 0, block scope but whole-program lifetime), register (in a CPU register).
- Recursion needs a base case. factorial(5) = 120; the Fibonacci series is 0 1 1 2 3 5 8 13 21 34. Recursion is shorter but uses a stack frame per call.
- A structure groups members of different types, each with its own memory; its size is the sum of the members. A union overlays its members in one block the size of the largest, so only the member written last is valid. Members are reached with .; an array of structures stores many records.
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The syllabus asks for
- Programming paradigms: procedural, structural and object oriented
- Features of OOP: Class, Object, Polymorphism and Inheritance
- Advantages of OOP
- Application of OOP
Key points
- A paradigm is a style of organising a program: procedural (functions on shared data), structured (procedural with only sequence/selection/iteration and modules), object-oriented (data and behaviour bundled into objects).
- A class is a blueprint binding data members and member functions; an object is an instance of a class with its own copy of the data.
- A constructor has the class's name, no return type, and runs automatically at creation; the destructor ~Class() runs at destruction. In inheritance, constructors run base→derived and destructors derived→base.
- Encapsulation bundles data with methods; data hiding follows from private; abstraction exposes only the interface. private = class only, protected = class + derived, public = everywhere.
- Inheritance (single, multilevel, multiple, hierarchical, hybrid) gives reuse and expresses "is-a"; the derived class inherits with class D : public B.
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The syllabus asks for
- Software Project Concept
- Concept of software development process
- Concept of SDLC life cycle
- System Analyst vs Software Engineer
- Requirement Collection Methods
- Concept of system design
- Software and quality
- Software development models: waterfall, prototype, agile
Key points
- A software project is a temporary, planned effort constrained by scope, time, cost and quality; effort is measured in person-months and adding people late does not buy time.
- The software development process = specification, design and implementation, validation, evolution. A process model arranges those in time.
- The SDLC phases are preliminary investigation, feasibility study, analysis, design, coding, testing, implementation and maintenance; maintenance takes 60–70 % of lifetime cost and is corrective, adaptive, perfective or preventive.
- The system analyst answers what (SRS, DFDs, talks to users); the software engineer answers how (design, code, tests).
- Requirements are collected by interview, questionnaire, observation, document review, JAD workshops, prototyping and brainstorming, and are written into an SRS that must be unambiguous and verifiable.
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The syllabus asks for
- Artificial Intelligence (AI) and Robotics
- Cloud Computing
- Big Data
- Virtual Reality
- e-commerce, e-medicine, e-governance
- Mobile Computing
- Internet of Things (IoT)
Key points
- AI builds machines that do jobs needing intelligence (coined 1956); machine learning ⊂ AI, deep learning ⊂ ML, generative AI/LLMs ⊂ deep learning. Types: narrow (all real systems today), general, super.
- A robot senses, decides and acts: sensors → controller → actuators → end effector, with feedback. Types: industrial, mobile, humanoid, medical, drone, exploration.
- Cloud computing rents computing over the internet, pay-per-use. Service models IaaS, PaaS, SaaS; deployment models public, private, community, hybrid; five NIST characteristics; it trades capital cost for dependence on a provider and a link.
- Big data = volume, velocity, variety, veracity, value; handled by Hadoop, Spark and NoSQL rather than one server. World data creation was about 181 ZB in 2025.
- VR replaces sensory input with a computer-generated 3-D world; needs an HMD, tracking, interaction devices and a fast engine; classified non-immersive, semi-immersive, fully immersive; AR adds to the real world, MR anchors to it.
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Objective questions
Computer Science: Unit-wise Objective Question Bank
Subjective questions
Computer Science: Unit-wise Subjective Question Bank
Model sets and predicted questions
Computer Science: Model Question Sets and Predicted Questions
Exam guide
The NEB Grade 12 Examination: Pattern, Grid and Strategy
The paper
2hr, FM 50 written (+25 practical +25 internal)
| Section | Questions | Marks each | Total |
|---|---|---|---|
| Group A MCQ | 9 | 1 | 9 |
| Group B short | 5 | 5 | 25 |
| Group C long | 2 | 8 | 16 |
Where the hours go
Teaching hours are the board's guide to how much of the paper each part carries.
- Unit 2 · Data Communication and Networking15 h
- Unit 1 · Database Management System (DBMS)12 h
- Unit 3 · Web Technology II12 h
- Unit 4 · Programming in C12 h
- Unit 5 · Object-Oriented Programming (OOP)10 h
- Unit 6 · Software Process Model (SPM)10 h
- Unit 7 · Recent Trends in Technology9 h