ISRO Scientist/Engineer SC (Computer Science) study materials
ISRO Scientist/Engineer SC (Computer Science) study resources

ISRO Scientist/Engineer SC (Computer Science) study plan

ISRO Scientist/Engineer SC (Computer Science) · Give each week a clear focus.

8 weeks · About 8 hours per week

Week 1

Programming and Data Structures

  • Implement from scratch in C a dynamic array, singly and doubly linked list, array-based and linked stack, and a circular queue; test each against edge cases (empty, single element, full, wraparound).

  • Tabulate the best/average/worst-case time and space complexity of every operation you implemented and justify each entry in one sentence.

  • Hand-trace recursion examples (factorial, Tower of Hanoi, decimal-to-binary, Ackermann for small inputs) by drawing the full call stack and counting calls.

  • Convert infix to postfix/prefix and evaluate postfix expressions by hand for 10 mixed-operator expressions with parentheses.

  • Solve 40 MCQs on arrays, linked lists, stacks, queues and hashing basics, and log every wrong answer with the corrected rule.

Your checkpoint

A notebook of 6 working C programs with an operation-complexity table, plus a 40-question error log at accuracy of at least 75%.

Week 2

Programming and Data Structures & Digital Logic and Computer Organization

  • Implement BST insert/delete/search (all three delete cases), min-heap insert/delete, and all five traversals; state worst-case complexity of each and when it degrades.

  • Solve 30 MCQs on tree/heap properties: node count vs height bounds, AVL rotation identification, complete-binary-tree array indexing, heapify cost, and open vs chained hashing collision behaviour.

  • Convert numbers among binary, octal, decimal and hexadecimal; compute 1's and 2's complement and state the signed range for 8-, 16- and 32-bit words.

  • Simplify 20 Boolean expressions with Karnaugh maps (including don't-care conditions) and redraw each result using only NAND gates, then only NOR gates.

Your checkpoint

A sheet of 20 K-map simplifications with final NAND-only and NOR-only circuits, plus a 30-question MCQ log at accuracy of at least 75%.

Week 3

Digital Logic and Computer Organization & Engineering Mathematics and Discrete Mathematics

  • Design and analyse flip-flop circuits: mod-N ripple and synchronous counters, ring and Johnson counters, and shift registers; write the state table and excitation table for each.

  • Compute cache behaviour for direct-mapped, set-associative and fully associative caches: split addresses into tag/index/offset, calculate hit ratio and AMAT, and classify compulsory, capacity and conflict misses.

  • Analyse a 5-stage pipeline: compute speedup, CPI with stalls, and identify data, control and structural hazards with the forwarding or stalling fix for each.

  • Prove or disprove set identities, check whether a given relation is reflexive/symmetric/transitive, identify posets, lattices and groups, and negate quantified statements correctly.

  • Solve 30 MCQs on computer organization and 25 on discrete mathematics, logging every formula you had to look up.

Your checkpoint

A one-page formula sheet (CPI, AMAT, speedup, address-bit splitting, counter design steps) plus a 55-question log at accuracy of at least 70%.

Week 4

Algorithms & Engineering Mathematics and Discrete Mathematics

  • Solve 15 recurrences using the Master Theorem and the substitution method, and state which case applies and why.

  • Hand-trace Dijkstra, Bellman-Ford, Prim, Kruskal and Floyd-Warshall on small weighted graphs; state complexity, correctness preconditions and which graph types break each algorithm.

  • Contrast dynamic programming with greedy for LCS, 0/1 vs fractional knapsack, matrix-chain multiplication and coin change; write the recurrence and base case for each.

  • Solve counting and graph-theory problems: pigeonhole, permutations with repetition, inclusion-exclusion, Euler/Hamiltonian path tests, chromatic number, and spanning-tree counting.

  • Take a 90-minute timed set of 40 algorithm and 20 discrete-mathematics questions and produce an error analysis grouped by cause.

Your checkpoint

A timed 60-question mock scored at least 65%, with a written error analysis listing the three weakest sub-topics to revisit.

Week 5

Theory of Computation and Compiler Design

  • Construct DFAs and NFAs for 10 given languages, convert two NFAs to DFAs by subset construction, and minimise one DFA using table filling.

  • Apply the pumping lemma to prove non-regularity for regular-looking languages and to prove non-context-freeness for at least two languages; list closure properties of regular and context-free languages.

  • Design PDAs for three languages and Turing machines for two, then place each language in the Chomsky hierarchy and classify it as regular, CFL, recursive or recursively enumerable.

  • Build an LL(1) parsing table using FIRST/FOLLOW sets and an SLR(1) table using LR(0) items; identify and explain every conflict that arises.

  • Generate three-address code and basic blocks for a given code fragment, build its DAG, and mark common subexpressions, dead code and loop-invariant statements.

Your checkpoint

A double-sided A4 automata-and-parsing cheat sheet (subset construction, FIRST/FOLLOW, LL(1) and SLR rules) plus a 30-question MCQ log at accuracy of at least 70%.

Week 6

Operating Systems

  • Compute waiting, turnaround and response times for a 5-process set under FCFS, SJF, SRTF, round-robin and priority scheduling, drawing the Gantt chart for each.

  • Write semaphore or monitor solutions for producer-consumer, readers-writers and dining philosophers, and check each against the four deadlock conditions.

  • Apply Banker's algorithm to a given allocation/available matrix to find a safe sequence, and identify the request that must be denied.

  • Compute effective access time with TLB and page faults, and count page faults under FIFO, LRU and Optimal for a given reference string; detect Belady's anomaly.

  • Compute total head movement for FCFS, SSTF, SCAN, C-SCAN and LOOK disk scheduling on the same request queue.

Your checkpoint

A fully worked set of 25 numerical OS problems with intermediate steps shown, plus 30 MCQs at accuracy of at least 70%.

Week 7

Database Management Systems & Software Engineering

  • Normalise six relations to 3NF and BCNF: compute attribute closures and candidate keys, show each violated FD, and verify the decomposition is lossless and dependency-preserving.

  • Write and actually run 30 SQL queries covering multi-table joins, GROUP BY/HAVING, nested and correlated subqueries, views and triggers; give the relational-algebra form of five of them.

  • Analyse B+ tree order and index choice for given queries, and explain 2PL, timestamp ordering, isolation levels and log-based recovery with checkpoints on a small schedule.

  • Draw ER, DFD and use-case diagrams for a supplied problem statement, compute cyclomatic complexity from a flow graph, and map out unit/integration/system/acceptance testing responsibilities.

Your checkpoint

A SQL script file of 30 queries executed successfully on a local MySQL or PostgreSQL instance, plus a 40-question DBMS/software-engineering log at accuracy of at least 70%.

Week 8

Computer Networks & Programming Languages and Web Technologies

  • Solve 20 numerical networking problems: CIDR subnetting, CRC generation and checking, checksum, sliding-window efficiency, CSMA/CD minimum frame size, token bucket and TCP congestion window growth.

  • Trace TCP's three-way handshake and state transitions, compare TCP and UDP headers, work through IP fragmentation, and order the steps of ARP, DHCP and DNS resolution against the OSI and TCP/IP layers.

  • Distinguish static vs dynamic scoping, value vs reference vs name parameter passing, and type checking vs coercion; write and read small HTML/CSS/JavaScript/XML/JSON snippets and explain HTTP methods, status codes and servlet/JSP lifecycle.

  • Complete two full-length timed mocks of 90 minutes spanning all ten domains, then compress every remaining formula and definition into a single revision page for the last day.

Your checkpoint

Two completed mock papers each scored at least 60%, plus a one-page revision sheet covering formulas and definitions from all ten domains.

Milestones

Week 4: Score at least 65% on the timed 60-question algorithms + discrete-mathematics mock, and confirm the data-structures, digital-logic and mathematics formula sheet covers every topic listed for weeks 1-4 with no blank entries.

Week 6: Solve all 25 numerical OS problems without looking at a solution key, score at least 70% on both the theory-of-computation/compiler and OS question sets, and be able to write an LL(1) table and a Banker's safe sequence from scratch in under 15 minutes each.

Week 8: Score at least 60% on both full-length mocks with no domain below 50%, and finish with a single-page revision sheet that fits on one side of A4 and covers all ten domains.