IBM Firmware Developer Interview Questions and Answers for Experienced

Q1. What is difference between Normal OS and RTOS? What is difference between microcontroller and microprocessor? Write a C program to swap two numbers without using 3rd variable.
Ans. 
RTOS is a real-time operating system designed for time-sensitive applications. Microcontrollers are integrated circuits with built-in memory and peripherals.
• RTOS is designed to provide deterministic and predictable response times for critical tasks.

• Normal OS is designed for general-purpose computing and may not prioritize real-time tasks.

• Microcontrollers are typically used in embedded systems and have limited resources...read more
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Q2. What is storage class in C?
Ans. 
Storage class in C determines the scope, visibility, and lifetime of variables.
• C has four storage classes: auto, register, static, and extern.

• Auto storage class is the default and is used for local variables.

• Register storage class is used for variables that should be stored in CPU registers for faster access.

• Static storage class is used for variables that retain their values between function calls.

• Extern storage class ...read more
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Q3. What is difference between macro and constant variable in C? How to divide a number without using division operator?
Ans. 
A macro is a preprocessor directive that is replaced by its value before compilation, while a constant variable is a read-only variable.
• Macros are defined using the #define directive, while constant variables are declared using the const keyword.

• Macros are replaced by their values during preprocessing, while constant variables are stored in memory.

• Macros can lead to code duplication, while constant variables provide ty...read more
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Q1. Basic question from my Resume and Work/Projects
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Q2. Technical Question : Stackoverflow, Queue, Virtual Class/Keyword, Pointers, Linked List
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Q3. Memory Stack, Local/Glabal/Staic Variable stored where?
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Q4. Direct Memory Access, Heap, Stack, Dyanamic Memory Allocation, memory Segmentation fault
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Q5. Difference between Timer and counters?
Ans. 
Timers are used to measure time intervals, while counters are used to count events or occurrences.
• Timers are typically used for generating delays, measuring time intervals, or triggering events at specific times.

• Counters are used to count external events, such as pulses or interrupts.

• Timers can be used to implement software delays, while counters can be used for tasks like frequency measurement.

• Examples: A timer can be...read more
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Online c programming test using online tool

Q1. Manager level round - explain about project and area of difficulty in embedded. Which one we work and fix issue
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Q1. Discuss about offer letter
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Very basic c questions like an array

Q1. It's about C programming and data structure and Embedded Questions
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Q1. High level C programming questions and project explanation
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Q1. Offer, salary Discussion
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Q1. Asked regarding programs
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Q2. Asked regarding questions of memory structure
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Q3. What is Compilation process
Ans. 
Compilation process is the process of converting source code into machine code by a compiler.
• Source code is written in a high-level programming language

• Compiler translates the source code into assembly code

• Assembler converts the assembly code into machine code

• Final executable file is generated
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Q1. What is pointer
Ans. 
A pointer is a variable that stores the memory address of another variable.
• Pointers are used to access and manipulate memory directly.

• They are often used in programming languages like C and C++.

• Example: int *ptr; // declares a pointer to an integer variable
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Q2. What is stack ?
Ans. 
Stack is a data structure that follows Last In First Out (LIFO) principle, used for storing temporary data in a program.
• Stack is a linear data structure with two main operations: push (adds data) and pop (removes data).

• Example: function call stack in programming languages like C, where function calls are added and removed in a LIFO manner.

• Stack memory is used for local variables and function call management.

• Stack overf...read more
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Q1. What are storage classes
Ans. 
Storage classes in C define the scope and lifetime of variables.
• Storage classes include auto, register, static, extern, and typedef.

• Auto variables are local to the block they are declared in.

• Register variables are stored in CPU registers for faster access.

• Static variables retain their value between function calls.

• Extern variables are declared in one file and can be used in another file.

• Typedef is used to create new dat
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Q2. What is use of device drivers
Ans. 
Device drivers are software programs that allow the operating system to communicate with hardware devices.
• Device drivers act as a translator between the hardware device and the operating system.

• They provide a standardized interface for the operating system to interact with different types of hardware devices.

• Device drivers help improve system stability and performance by enabling efficient communication between hardwar...read more
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Q3. How do you copy files from and device to other
Ans. 
You can copy files from one device to another by using file transfer protocols like FTP, SCP, or by physically transferring the files via USB or external storage devices.
• Use FTP (File Transfer Protocol) to transfer files over a network

• Use SCP (Secure Copy Protocol) for secure file transfers

• Physically transfer files by connecting devices via USB or using external storage devices like USB drives or SD cards
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Q4. Bit mask operation
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Q5. Swapping without 3 rd variable
Ans. 
Swapping two variables without using a third variable
• Use XOR operation: a = a ^ b; b = a ^ b; a = a ^ b;

• Use addition and subtraction: a = a + b; b = a - b; a = a - b;

• Use multiplication and division: a = a * b; b = a / b; a = a / b;
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