**Tips for ISRO Preparation 2021**

I am going to give tips about **ISRO Preparation 2021 **for Scientist/Engineers written exam of computer engineering or information technology branch which are as follows.

- Solve all the previous
**GATE papers**from 1991 to 2021. - Solve all the previous
**ISRO written test papers**.

ISRO generally asks question from previous GATE papers so you have to solve all the questions from the previous GATE papers with full of understanding.

If ISRO changes single concept and you will be able to give answer for that question. Topics that have been asked in the ISRO Exam so far are as follows.

**Topics of Technical Subjects for ISRO Preparation 2021**

**1) Operating System’s topics for ISRO Preparation 2021:**

- Parity concept in the RAID level
- SATA cable
- Use of Bankers algorithm
- Fork concept
- Page replacement algorithm i.e. number of page fault
- Mutual exclusion
- Disk related concept i.e. no of sectors, no of tracks, disk capacity, no of bits required to address disk.
- Disk drive system i.e. no of cylinder, sectors per cylinder etc.
- Critical region
- Semaphore value calculation i.e. binary and counting semaphore
- Hard real time system and soft real time system
- Effective access time of memory examples
- No of resources and no of processes required not to occur or occur deadlock
- Working set model
- Examples using physical address space, logical address space, no of pages in the logical address spaces, no of frames in the physical address space, TLB size
- Process scheduling algorithm and its application
- Disk scheduling algorithm and its application.
- Belady’s anamoly
- Process scheduling algorithm to implement real time operating system
- Application of semaphore
- Application of monitor
- Dirty bit concept
- DISC scheduling algorithm
- Segmentation examples
- Types of decoder required in building memory
- Define thrashing
- Necessary condition for deadlock
- Process state diagram with transition label
- What is embedded pointer
- Working set model example
- What is priority inversion problem
- What is livelock

**2) Computer Network’s topic for ISRO Preparation 2021:**

- Topology of all the Ethernet technologies
- STP and UTP cable
- IP address classes
- Subnet mask related questions
- Supernet mask related quetions
- Mess topology, no of cables required
- Protocols SMTP
- Access control protocol
- Ethernet frame
- Ip header
- TCP header
- Gateway protocol
- Wireless protocol
- Bit stuffing and byte stuffing
- Static and dynamic routing protocol
- Application layer protocol with theirs transport layer protocol
- Ip allocation protocol ( DHCP, RARP, BOOTP, ARP)
- Token ring concept with formula.
- CRC calculation.
- Sliding window protocol with formula
- DNS Protocol
- Hijacking, spoofing, snooping concept
- Frequency spectrum ranges i.e. range of infrared, microwave, satellite, radar
- No of characters in the asynchronous and synchronous communication need to transfer concept
- Flags in the TCP header and its sequence number concept.
- ALOHA concept with formula
- PING and ICMP protocol concept
- Layers of OSI and TCP/IP model and don’t forget to make notes for process to process, host to host , device to device layer
- What is Port Address Translation, Network address translation, address mapping and port mapping
- What is autosense, synchronization, pinging and auto negotiation transmission technology with respect to Ethernet
- IP header example like using HLEN, fragment offset value.
- Different meaning of first 8 bit of the IP packets
- What is grid computing, neural network, parallel processing and cluster computing?
- Hamming code example such as find number of bits required to correct single bit.
- Broadcast domain and collision domain in layer-2, layer-3, bridge, router
- Properties of IPV6 protocol
- Properties of IPV4 protocol
- Traffic shapping algorithm such as solid bucket algorithm,spanning tree,hockey helm and leaky bucket algorithm
- Types of firewall or gateway
- Different name of data in different layer like application(message), transport(segment), network(datagram), data link layer(frame), physical (protocol data unit)
- Encoding techniques used in giga ethernet technology
- What is RBS, Hopfield, Back Propagation and Kohonen
- What is RARP and ARP protocol
- What is SSL, IPSec and its position in the network model
- How to calculate hamming distance
- What is LDAP
- What is the aggregate bandwidth of SAN switch
- What is the size of MAC, IP and PORT address
- Different format of MAC address such as for broadcasting
- Advantages, disadvantages, purpose of VLAN

**3) Data Structure’s topic for ISRO Preparation 2021:**

- Linked list.
- No of iteration in bubble sort after specific state
- Tree traversal
- Pointer affected while perform operation With singly, doubly linked list.
- Application of stack, queue, linked list, tree , graph data structure.
- infix, postfix and prefix.
- Evaluation of postfix or prefix expression using stack
- Hashing collision resolution techniques
- No of maximum and minimum noded in different types of binary trees i.e. binary search tree, complete binary tree etc.
- One sorted array is given, then they ask to apply binary search on it, then they will ask to calculate average search for each element.
- How many number of binary trees can be formed using n vertice( use formula).
- AVL tree rotation, insertion and deletion
- What is hashed file, indexed file, B-Tree and Sequential file
- Maximum and minimum number of nodes in full binary tree
- Maximum and minimum number of nodes in complete binary tree
- Number of nodes with respect to height related question
- Average of depth of binary search tree

**4) Design and Analysis of Algorithm’s topic for ISRO Preparation 2021:**

- P, NP, NP-Complete theory
- Recurrence relation of divide and conquer algorithm
- Masters theorem to find complexity
- DFS and BFS traversal
- Shortest path algorithm
- Prims algorithm
- Krushkal algorithm
- Bellman ford algorithm
- Floyd war shall algorithm
- Time complexity
- Space complexity
- Complexity calculation from the code
- No of comparision required in sorting techniques
- Algorithm and its design technique
- Tracing of each sorting algorithm such as greedy method, backtracking, dynamic programming and divide and conquer

**5) Programming Language’s topic for ISRO Preparation 2021:**

- Pass by value and pass by reference
- How to read pointer related statement.
- Output of the program.
- Shift operators
- Signed, unsigned integer
- Storage classes i.e. register, global, static and auto or local variable
- Malloc, calloc, Realloc and free function
- Macro concept
- File functions
- Size of structure and union
- Left shift and right shift operator
- Examples of pre-increment, pre-decrement, post-increment and post-decrement operator.
- Find out number of elements in one, two and three dimensional array
- What is dynamic scooping and static scooping
- What is deep binding and shallow binding
- Recursion

**6) Digital Logic Design’s topic for ISRO Preparation 2021:**

- Minimum number of NAND gates required to build OR, AND, NOT, Ex-OR and Ex-NOR, NOR gates, implement Boolean function
- Minimum number of NOR gates required to build OR, AND, NOT, Ex-OR and Ex-NOR, NAND gates, implement Boolean function
- Minimum number of NAND gates and NOR gates to implement particular Boolean function.
- Binary addition
- Truth table of all the Logic GATES
- Boolean expression from the logic circuit
- Logic circuit from the Boolean function
- Boolean function for half adder
- Boolean function for full adder
- Boolean function for half subtractor
- Boolean function for full subtractor
- Redundant path
- To find redundant gate
- Hazard in logic circuit
- Circuit for binary code
- POS, SOP Boolean expression
- Boolean expression minimization
- Boolean expression from K-Map
- K-Map
- Flip-flop and its characteristic equation
- Logic circuit for excess-3, gray code, BCD code, Hamming Code
- SR flip-flop, RS flip-flop, T flip-flop and D flip-flop
- No of flip-flops require to build ring counter, Johnson counter, synchronous counter, asynchronous counter
- No of 1’s in the binary representation of the expression and no of 0’s in the binary representation of the expression.
- No of independent variables in the Boolean function
- To find delay of the Boolean logic circuit
- Rules of Boolean algebra
- Construction of higher order multiplexer using lower order multiplexer ( use formulas )
- Construction of higer order decoder using lower order decoder( user formulas )
- Properties of Logic families such as CMOS, ECL, TTL

**7) Computer Organization and Architecture’s topic for ISRO Preparation 2021:**

- RAM chip calculation
- Addressing modes
- Code conversion
- 1’s and 2’s complement
- Examples using pipelining concept like efficieny, speed factor etc.
- Flynn’s Texonomy
- Solution of Data hazard
- Solution of Control hazard
- IEEE 754 32 bit and 64 bit floating point representation
- Range of integers for sign magnitude, 1’s complement and 2’s complement general formula
- What is access, cycle, rotational, latency time
- To find number of wait states using CPU frequency, memory access time and other delay
- No of logical CPUs in Physical quad core chips with or without hyper threading
- Types of decoder required in building memory
- How many number of BCD codes can be stored in 12 switches(on/off switch only two states)
- Calculate page table size( with dirty bit, valid/invalid bit etc.)
- Rules of BCD addition and BCD subtraction
- Rules of Excess-3 addition and subtraction
- Examples of DMA concept
- Associative memory
- Examples of cache memory
- What is cycle stealing technique of DMA?
- What is burst transfer techniques of DMA?

**8) Database Management System’s topic for ISRO Preparation 2021:**

- Data dictionary
- Transaction protocol
- ACID properties of transaction
- ER diagram
- SQL query
- B tree and B+ tree insertion, deletion
- B tree and B+ tree, equation to calculate order of Node.
- Relational algebra JOIN operation
- Primary key and foreign key concept
- Referencing and referenced relation
- Trigger basic basic concept
- Stored procedure basic concept
- Cursor basic concept
- Indexing
- On delete cascade concept
- Undo and redo operation of transaction.
- No of records in the block that is blocking factor, no of block pointer concept
- To find functional dependencies from the given set of the functional dependencies
- Types of Symbols used for aggregation, association in ER diagram
- Properties of decomposition i.e. lossless join, dependency preserving
- Multivalue dependency concept
- Isolation level in DBMS such as serializable, repeated read, committed read and uncommitted read
- Normalization with example
- Armstrong’s axioms, Armstrong’s inference

**9) Theory of Computation’s topic for ISRO Preparation 2021:**

- Recursive language theory concept
- DFA and NFA concept
- Average access time using cache and main memory related example
- CFG properties
- Language from the grammar and regular expression.
- Type-0, type-1, type-2 and type-3 grammar
- Derivation of string from grammer

**10) Compiler Design for ISRO Preparation 2021:**

- Use Phases of compiler
- Data structure use for symbol table construction.
- Classification or top down and bottom up parser.
- Examples of top down parser and bottom up parser.
- Code optimization techniques
- Use of one pass and two pass assembler
- Peephole optimization
- No of tokens in the statement
- What is Yacc
- Properties of activation record
- What is left recursive grammar, how to remove left recursion
- What is left facturing of grammer, how to remove left facturing
- What is strength reduction
- Properties of Peephole optimization

**11) Microprocessor’s topic for ISRO Preparation 2021:**

- Interrupt address
- Little endian and big endian
- 8085 microprocessor instruction.
- Assembly language program
- Properties of Tri-State Buffer
- Flags in 8085 and flag status after each instruction
- Address location of RST 7.5, RST 6.5, RST 5.5 and TRAP
- Vectored interrupt
- Non vectored interrupt
- Software interrupt
- Hardware interrupt
- Pin Diagram of 8085
- Pin diagram of 8086
- Pin diagram of 8151

**12) Internet Security’s topic for ISRO Preparation 2021:**

- Hashing algorithm
- IPSec, SSL
- PGP

**13) Software Engineering’s topic for ISRO Recruitment 2021:**

- COCOMO model equation
- UML diagram
- Objects
- CMMI level
- Life cycle model
- Cyclomatic complexity calculation.
- Types of maintenance
- Cohesion
- Coupling
- What is reliability, robustness, portability, scalability of the software
- Classification of functional and non functional requirement
- Software development model
- Software Testing concept
- Cyclomatic complexity of different modules such if, else if, else if ladder, for, while, do while
- Testing example from timothy Williams
- Advantages, disadvantages and limitation of spiral model
- Name of different levels of Data flow diagram
- Activity, package, class and sequence diagram

**14) Programming in C++’s topic for iSRO Preparation 2021:**

- Overloaded operator
- Inheritance concept and types of inheritance
- Properties of reference variable
- Difference between reference variable and pointer variable
- Properties of extern, volatile, const and static storage class of variable.
- Types of constructor
- How to declare copy constructor syntax

**15) Web Technology’s topic for ISRO Preparation 2021:**

- Basics of XML
- Basic HTML tags.
- Basics of java script
- What is active, static, dynamic and passive web page?

**16) Linux’s topic for ISRO Preparation 2021:**

- Linux command

**17) Computer Graphics’s topic for ISRO Preparation 2021:**

- What is Pixel?
- Examples using z-buffer algorithm
- Example of row major order and column major order with frame buffer
- Calculate size of lookup table using RGB component.
- What is gourard shading, phong shading, constant shading and flat shading
- Properties of Z-buffer algorithm
- Examples of screen resolution
- Examples of calculation of interpolated values

**18) JAVA’s topic for ISRO Preparation 2021:**

- Super class of all errors and exceptions.
- Error in system.out.println() statement.
- System.math class

**19) Computer Maintainance’s topic for ISRO Preparation 2021:**

- Types of keyboard switch
- Data transfer speed of DVD, CD and Floppy disk

**20) Multimedi’s topic for ISRO Preparation 2021:**

- Algorithm to generate .png file
- Image types used in MPEG
- Compression ratio in mp3 file
- Compression ratio of audio

**21) Network Security’s topic for ISRO Preparation 2021:**

- RSA algorithm with example.
- AES
- RSA
- DES
- 3DES
- RC4
- Hash function
- Substitution techniques of encryption
- Transposition techniques of encryption
- What is SHA-1
- What is digital signature

**22) Other subject ’s topic for ISRO Preparation 2021:**

- What is IAAS, PAAS, SAAS, Architecture as a service
- What is raw throughput of USB 2.0 technology?
- What is opportunistic reasoning?
- IEEE number of input/output devices, different types of cable.
- Voltage level of RS-232
- What is warnier diagram
- What is n-type semiconductor and when it is heated
- What is p-type semiconductor and when it is heated

**Topics of Mathematics Subjects for ISRO Preparation 2021**

**1) Linear Algebra’s topic for ISRO Preparation 2021:**

- Find determinant of matrix
- Find adjoint of matrix
- Matrix multiplication
- Symmetric matrix
- Asymmetric matrix
- Skew symmetric matrix
- Rank of matrix

**2) Probability’s topic for ISRO Preparation 2021:**

- Simple probability question

**3) Numerical Method’s topic for ISRO Preparation 2021:**

- Classification of numerical method with names

**4) Set theory’s topic for ISRO Preparation 2021:**

- Symmetric difference of SET

**5) First order logic’s topic for ISRO Preparation 2021:**

- Tautology
- Contradiction

**6) Aptitude’s topic for ISRO Preparation 2021:**

- Simplification

**7) Limit topic for ISRO Preparation 2021:**

- Simple example of limit
- Refer its formula

**8) Graph topic for ISRO Preparation 2021:**

- Eular graph
- Basics of graph
- Maximum No of edges in the simple graph with loops
- Maximum No of edges in the simple graph without self loops.

**9) Simle Mathematics for ISRO Preparation 2021:**

- Examples of parabola
- Examples of hyperbola
- Maxima and Minima

**Previous Question Papers for ISRO Preparation 2021**

Previous Year Papers (Computer Science) |
Download Links |
---|---|

Computer Science 2018 | Download |

Computer Science 2017 (II) | Download |

Computer Science 2017 | Download |

Computer Science 2016 | Download |

Computer Science 2015 | Download |

Computer Science 2014 | Download |

Computer Science 2013 | Download |

Computer Science 2011 | Download |

Computer Science 2009 | Download |

Computer Science 2008 | Download |

Computer Science 2007 | Download |

Thank you for referring this article for upcoming ’s iSRO 2021 written exam for the scientist/engineers.

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## 3 comments

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