ISRO Scientist CS Syllabus 2026: Part A and Part B Topics
The ISRO Scientist CS syllabus is the set of Computer Science and aptitude topics tested in the ISRO computer based test (CBT) for Scientist/Engineer 'SC' posts. ISRO names the two parts of the test but does not publish a topic-wise list for either, so most aspirants build their plan from core CS subjects and previous papers.
This page gives a working topic checklist for the current cycle (Advertisement No. ISRO:ICRB:03(EMC):2026), shows which subjects overlap with GATE CS, and suggests how to order your preparation. The detailed marking rules sit on the ISRO Scientist CS exam pattern page.
Table of Contents
What ISRO officially says about the syllabus
ISRO names the tests in its advertisement but does not publish a topic-wise syllabus. Part A is described only as "Area/Discipline Specific" for Computer Science, and Part B as "Aptitude/Ability" covering numerical, logical, diagrammatic, abstract and deductive reasoning. The topic lists below are built from standard BE/B.Tech Computer Science subjects and from the questions in ISRO's own earlier papers. Use them as a working checklist, not as an official list.
The best official guide to depth and style is the question paper itself. ISRO has placed the Computer Science 2025 paper and the Computer Science 2023 paper on its recruitment page.
Syllabus at a glance
Part | Area | Questions | Marks | Time |
|---|---|---|---|---|
A | Discipline specific (Computer Science) | 80 MCQs | 80 | 90 minutes |
B | Aptitude and ability | Maximum 15 MCQs | 20 | 30 minutes |
Key changes to know
CBT format: The current advertisement describes a CBT with two timed parts. Older pages may still show earlier ISRO patterns, so rely on the current advertisement.
No GATE mention: The 2026 advertisement does not refer to GATE, so you cannot assume the syllabus follows the GATE CS list exactly.
Beyond the GATE list: Our reading of the 2025 paper shows questions on security and cryptography, big data, artificial intelligence and cloud computing. A GATE-only plan can miss these.
Part A: Computer Science topics
Part A is the scoring section, with 80 of 100 marks. The table groups subjects by how they are best studied.
Core subjects
Subject | Topics to cover | Start with |
|---|---|---|
Operating systems | Process and thread management, CPU scheduling, synchronisation and semaphores, deadlocks, memory management, paging and page replacement, virtual memory, file systems, disk scheduling | Scheduling and page replacement (tracing questions) |
Databases | ER model, relational algebra, SQL, normalisation, functional dependencies, transactions, concurrency control, indexing and B-trees | Normalisation and SQL |
Computer networks | OSI and TCP/IP layers, IP addressing and subnetting, routing, TCP flow and congestion control, error detection, application protocols, Wi-Fi and LAN basics | Subnetting and TCP window problems |
Digital logic | Number systems, Boolean algebra, K-maps, combinational and sequential circuits, flip-flops, counters, minimisation | K-maps and number systems |
Computer organisation and architecture | Instruction formats, addressing modes, pipelining, cache and memory hierarchy, I/O interfacing, ALU and control unit | Cache mapping and pipelining |
Data structures | Arrays, linked lists, stacks, queues, trees, heaps, hashing, graphs | Trees and hashing |
Algorithms | Asymptotic analysis, sorting and searching, divide and conquer, greedy methods, dynamic programming, graph algorithms, complexity classes | Recurrences and graph algorithms |
Theory of computation | Finite automata, regular expressions, context-free grammars, pushdown automata, Turing machines, decidability | Regular and context-free languages |
Compiler design | Lexical analysis, parsing (LL and LR), syntax-directed translation, intermediate code, code optimisation, runtime environments | Parsing tables |
Mathematics and programming
Engineering mathematics: Linear algebra (matrices, eigenvalues), calculus basics, probability and statistics.
Discrete mathematics: Propositional and predicate logic, sets and relations, combinatorics, graph theory, recurrence relations.
Programming: C and C++ output-tracing, pointers, recursion, object-oriented concepts, Java and JVM basics, regular expressions.
Software engineering: Development models, testing, coupling and cohesion, basic metrics.
Applied and emerging areas
These topics carry fewer questions, but they are usually conceptual and quick to score once you have read them once.
Area | Topics to cover |
|---|---|
Information security | Symmetric and public-key cryptography, RSA, hashing, digital signatures, IPSec and TLS, common attacks |
Artificial intelligence and machine learning | Search strategies, knowledge representation, supervised and unsupervised learning basics, neural network terms |
Big data | Hadoop ecosystem, MapReduce, NoSQL types, data warehousing concepts |
Cloud computing | Service models, deployment models, virtualisation, containers |
Web technologies | HTTP basics, markup and scripting concepts, client-server models |
In the visible part of the 2025 paper, operating systems, DBMS, digital logic, mathematics and security each supplied several questions, while networks, AI and big data also appeared regularly. This is our approximate reading and not an official weightage, so use it only to decide the order of revision.
Part B: aptitude and ability
ISRO lists the reasoning types but no sub-topics. The checklist below covers what these types normally include.
Reasoning type | What to practise |
|---|---|
Numerical | Percentages, ratio, averages, time and work, speed and distance, number series, basic data interpretation |
Logical | Syllogisms, seating arrangements, blood relations, direction sense, coding and decoding, statements and conclusions |
Diagrammatic | Venn diagrams, figure counting, mirror and water images, paper folding |
Abstract | Pattern and figure series, odd one out, matrices of figures |
Deductive | Premise-based conclusions, if-then reasoning, puzzles |
Overlap with GATE CS
If you have prepared for GATE CS, you already own most of Part A. The table shows where the overlap ends.
Area | GATE CS preparation | ISRO Scientist CS | How to plan |
|---|---|---|---|
Core subjects (OS, DBMS, CN, COA, TOC, compilers) | Deep, numerical | Same topics, often shorter questions | Revise from your existing notes and solve ISRO papers |
Mathematics | Heavy weightage | Present, moderate | Keep linear algebra and probability active |
Security, big data, AI, cloud | Limited or absent | Appear in papers | Add these as a separate short module |
General aptitude | Verbal and numerical | Reasoning-heavy Part B | Practise diagrammatic and abstract types separately |
Interview: is there a syllabus?
No topic list is published for the interview. The advertisement gives the marking scheme: technical knowledge (40 marks), general awareness related to the specialisation (20), presentation and communication (20), comprehension (10) and academic achievements (10). Revise your degree subjects, your final-year project and basic space-technology awareness. The full breakdown is on the exam pattern page.
How to cover the syllabus
Weeks 1 to 6, core concepts: Finish operating systems, DBMS, networks, digital logic and computer organisation first. Make short notes as you go.
Weeks 5 to 9, remaining subjects: Cover data structures, algorithms, theory of computation, compilers and mathematics. Add a 30-minute daily block for reasoning practice.
Weeks 8 to 10, applied areas: Read security, AI, big data and cloud in one pass, then revise with short topic tests.
Weeks 10 to 12, papers and mocks: Solve the 2023 and 2025 ISRO papers under time, then move to full-length mocks.
Final phase, analysis: Review every mock on the same day, update your error log and revise only weak topics.
Topic-wise practice helps most in the middle weeks. You can attempt ISRO Scientist CS online tests on Testkart by subject, and use the ISRO Scientist CS study notes guide to organise revision material. For the complete cycle details, return to the ISRO Scientist CS overview.
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