ISRO CS Syllabus 2026: Complete Scientist/Engineer SC Exam Guide

ISRO Scientist/Engineer SC 2026: Recruitment Overview

Computer Science candidates compete for a defined share of the total vacancies announced under this notification, with detailed post and centre wise numbers published in the official notification PDF. Given the limited number of seats and the technical depth of the exam, a clear topic wise preparation plan matters far more here than in a generic aptitude based government exam.

ISRO CS Eligibility Criteria

Before going into the syllabus, it helps to confirm that you meet the basic eligibility requirements.

Candidates should refer to the official notification PDF for the exact age reckoning date and any category specific relaxation applicable to their case, since these are fixed by ISRO for each recruitment cycle.

ISRO CS Exam Pattern 2026

The ISRO Scientist/Engineer written test for Computer Science is a computer based test divided into two parts, with a combined duration of 120 minutes.

Part A, the core Computer Science section, carries 80 percent of the total weightage in the written test, which makes it the section that should receive the overwhelming majority of your preparation time. Part B tests general reasoning ability and does not penalise wrong answers, so every question in this part should ideally be attempted.

ISRO CS Syllabus 2026: Part A, Computer Science and Engineering

The Part A syllabus for ISRO CS closely mirrors the standard undergraduate Computer Science curriculum and is structured very similarly to the GATE CS syllabus, which makes GATE level preparation material broadly relevant, though ISRO's own previous year papers should remain the primary reference for question style and difficulty.

Programming and Data Structures

• Programming in C
• Recursion
• Arrays, stacks, queues, linked lists, trees, binary search trees and binary heaps
• Graphs and their representations

Algorithms

• Searching, sorting and hashing techniques
• Asymptotic worst case time and space complexity analysis
• Algorithm design techniques: greedy method, dynamic programming and divide and conquer
• Graph traversal techniques, minimum spanning trees and shortest path algorithms

Theory of Computation

• Regular expressions and finite automata
• Context free grammars and push down automata
• Regular languages and context free languages, the pumping lemma
• Turing machines and undecidability

Compiler Design

• Lexical analysis, parsing and syntax directed translation
• Intermediate code generation
• Local optimisation techniques
• Data flow analysis: constant propagation, liveness analysis and common subexpression elimination
• Runtime environments

Operating System

• Concurrency and process synchronisation
• Deadlock, its causes and handling
• CPU scheduling and I/O scheduling
• Memory management and virtual memory
• File systems, system calls, processes, threads and inter process communication

Databases

• ER model and relational model
• Relational algebra, tuple calculus and SQL
• Integrity constraints and normal forms
• File organisation and indexing, including B and B+ trees
• Transactions and concurrency control

Computer Networks

• Concept of layering, OSI and TCP/IP protocol stacks
• Packet switching, circuit switching and virtual circuit switching
• Data link layer: framing, error detection, medium access control and Ethernet bridging
• Routing protocols: shortest path, flooding, distance vector and link state routing
• Fragmentation and IP addressing, IPv4, CIDR notation, and basics of IP support protocols such as ARP, DHCP and ICMP
• Network Address Translation (NAT)
• Transport layer: flow control, congestion control, UDP, TCP and sockets
• Application layer protocols: DNS, SMTP, HTTP, FTP and email

Digital Logic

• Boolean algebra
• Combinational and sequential circuits
• Minimisation techniques
• Number representations and computer arithmetic, both fixed and floating point

Computer Organization and Architecture

• Machine instructions and addressing modes
• ALU, data path and control unit design
• Instruction pipelining and pipeline hazards
• Memory hierarchy: cache, main memory and secondary storage
• I/O interface, including interrupt and DMA modes

ISRO CS Syllabus 2026: Part B, Aptitude and Ability

Part B is common in structure across all engineering disciplines and evaluates general reasoning ability rather than technical knowledge.

• Logical Reasoning
• Diagrammatic Reasoning
• Abstract Reasoning
• Deductive Reasoning

Since there is no negative marking in this part, candidates should attempt every question, even ones they are not fully confident about, since an educated guess carries no penalty here, unlike in Part A.

ISRO CS Qualifying Marks

ISRO applies a minimum qualifying criterion across both parts of the written test, not just an overall cut off.

This means a candidate needs to clear the sectional minimum in both Part A and Part B individually, in addition to meeting the overall aggregate requirement, to be considered for the next stage.

Selection Process After the Written Test

Candidates who clear the qualifying marks in the written test are shortlisted for a Personal Interview. Final selection is based on a combined score, with 50 percent weightage given to the written test and 50 percent weightage given to the interview. This equal split makes the interview stage just as decisive as the written exam, and candidates should not treat qualifying the written test as the finish line.

ISRO Scientist/Engineer SC Salary

Selected candidates are appointed at a starting basic pay of Rs 56,100 per month, in Pay Level 10 of the 7th Central Pay Commission. With dearness allowance, house rent allowance, transport allowance and other applicable benefits, the gross monthly salary works out to approximately Rs 70,000 to Rs 80,000, with an in hand take home salary of roughly Rs 60,000 or more, depending on the posting location and applicable allowances.

How to Prepare for the ISRO CS Exam

Given the syllabus overlap with GATE Computer Science and the discipline specific nature of the written test, a structured preparation approach works better than generic revision.

• Since Part A carries 80 percent of the total marks, prioritise subjects where you can build strong conceptual clarity quickly, particularly Operating Systems, Computer Networks, DBMS and Digital Logic, which tend to have more direct, formula and concept based questions compared to Theory of Computation or Compiler Design
• Solve ISRO's own previous year question papers for Computer Science, since the difficulty level and question framing style is distinct from GATE, even though the topics overlap significantly
• Because of the 0.33 negative marking in Part A, avoid guessing on questions where you have no partial concept clarity, since three wrong answers can offset one correct answer
• Attempt every question in Part B, since it carries no negative marking and rewards even a reasonably confident guess
• Time yourself strictly during practice, since 90 minutes for 80 technical questions leaves very little room for questions that take more than a minute or two to solve
• Revise Computer Organization, Digital Logic and Data Structures numerically, since these subjects often carry calculation based questions that are quick to solve once the method is clear

Frequently Asked Questions

What is the ISRO CS syllabus 2026 based on? The syllabus covers Programming and Data Structures, Algorithms, Theory of Computation, Compiler Design, Operating Systems, Databases, Computer Networks, Digital Logic, and Computer Organization and Architecture, along with a separate Aptitude and Ability section.

How many questions are asked in the ISRO CS written exam? The exam has 95 questions in total, 80 in Part A on Computer Science and 15 in Part B on Aptitude and Ability, for a combined 100 marks.

Is there negative marking in the ISRO CS exam? Yes, Part A carries a negative marking of 0.33 marks for each wrong answer. Part B has no negative marking.

What are the minimum qualifying marks for ISRO CS 2026? Unreserved candidates need at least 50% in each part and 60% aggregate. PwBD candidates need at least 40% in each part and 50% aggregate.

How is the final selection made for ISRO Scientist/Engineer SC? Final selection is based on a combined score with 50% weightage from the written test and 50% weightage from the interview.

What is the salary of an ISRO Scientist/Engineer SC? The starting basic pay is Rs 56,100 per month in Pay Level 10, with a gross monthly salary of approximately Rs 70,000 to Rs 80,000 including allowances.

Is GATE CS preparation useful for the ISRO CS exam? Yes, the topic coverage is very similar to the GATE Computer Science syllabus, so candidates with a GATE preparation background will find most topics familiar, though it is still important to practice ISRO's own previous year papers for the specific question style and negative marking pattern used in this exam.