CS Theory Notes for Technical Interviews
W Code provides comprehensive Computer Science theory notes covering Operating Systems, DBMS, Computer Networks, and OOPs. Each topic includes concept explanations, diagrams, and frequently asked interview questions for TCS, Infosys, Wipro, and FAANG technical rounds.
Definition
W Code CS Theory Notes is a free, interview-focused collection of Computer Science fundamentals covering Operating Systems, Database Management Systems, Computer Networks, and Object-Oriented Programming. Unlike academic textbooks, these notes are designed specifically for technical interview preparation at Indian IT companies and product-based organizations.
Four Core CS Subjects
Operating System (OS)
Process management, CPU scheduling, memory management, deadlocks, file systems, and synchronization concepts.
- • Process vs Thread differences
- • CPU scheduling algorithms (FCFS, SJF, RR)
- • Deadlock prevention, avoidance, detection
- • Virtual memory and paging
- • 50+ interview questions
Database Management (DBMS)
Relational model, SQL queries, normalization, transactions, indexing, and advanced database concepts.
- • ER diagrams and normalization (1NF-BCNF)
- • SQL: Joins, subqueries, aggregations
- • ACID properties and transactions
- • Indexing: B-Tree, Hash indexing
- • 60+ interview questions
Computer Networks (CN)
OSI/TCP-IP models, protocols (HTTP, TCP, UDP, DNS), IP addressing, routing, and network security basics.
- • OSI vs TCP/IP model comparison
- • TCP vs UDP differences
- • IP addressing and subnetting
- • HTTP/HTTPS, DNS, DHCP
- • 45+ interview questions
Object-Oriented Programming (OOPs)
Four pillars of OOPs, design patterns, SOLID principles with examples in Java and Python.
- • Encapsulation, Inheritance, Polymorphism, Abstraction
- • Abstract class vs Interface
- • SOLID principles explained
- • Design patterns (Singleton, Factory)
- • 50+ interview questions
Top 10 Most Asked CS Questions in Interviews
- 1.What is the difference between Process and Thread?
- 2.Explain ACID properties in DBMS.
- 3.What are the differences between TCP and UDP?
- 4.What is the difference between Abstract Class and Interface?
- 5.Explain different CPU scheduling algorithms.
- 6.What is normalization? Explain 1NF, 2NF, 3NF, BCNF.
- 7.What is the OSI model? Explain each layer.
- 8.What is deadlock? How to prevent it?
- 9.Explain the four pillars of OOPs.
- 10.What is virtual memory and paging?
Frequently Asked Questions
Which CS subjects are asked in TCS technical interviews?
TCS technical interviews primarily focus on DBMS (SQL queries, normalization), OOPs (four pillars, polymorphism), and basic OS concepts. Computer Networks is occasionally asked. W Code covers all these topics with TCS-specific frequently asked questions.
How important is CS theory for placement interviews?
According to W Code's analysis, 40-50% of technical interview questions come from CS fundamentals (OS, DBMS, CN, OOPs). While DSA tests your problem-solving ability, CS theory questions assess your core computer science knowledge. Both are equally important for placement success.
How long to prepare CS theory for interviews?
With 1 hour of daily study using W Code's interview-focused notes, you can cover all four subjects in 3-4 weeks. Focus on understanding concepts rather than memorizing, and practice explaining answers out loud as you would in an interview.
"Understanding OS, DBMS, CN, and OOPs isn't optional for placements—it's the foundation that interviewers use to assess if you truly understand computer science."— Bhanu Bisht, Founder of W Code
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