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“Embedded Systems Frequently Asked Questions in various Embedded System Interviews asked by the interviewer. So learn Embedded Systems with the help of this Embedded System Interview questions and answers guide and feel free to comment as your suggestions, questions and answers on any Embedded System Interview Question or answer by the comment feature available on the page.”



21 Embedded System Questions And Answers

3⟩ Explain What are the features different in pSOS and vxWorks?

Actually theres not much of difference between using psos or vxworks.A few differences in features are:

1.The psos priority is reverse of vxworks.

2.psos supports posix 1003.1 while vxworks it is 1003.1b.

3.In psos device driver architecture is different than vxworks.

4.Also vxworks has interrupt

latency<4.33 microsecs while psos its higher.

Other then these both work in same manner and follow same

architecture.

Also as psos is getting killed no fresh development work is supported by windriver for psos. Also vxworks development environment is much more user friendly then psosenvironment becos vxworks IDE mimics mostly visual studio.

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6⟩ Explain What are different qualifiers in C?

1) Volatile:

A variable should be declared volatile whenever its value could change unexpectedly. In practice, only three types of variables could change:

► Memory-mapped peripheral registers

► Global variables modified by an interrupt service routine

► Global variables within a multi-threaded application

2) Constant:

The addition of a 'const' qualifier indicates that the (relevant part of the) program may not modify the

variable.

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7⟩ Explain What are the different qualifiers in C?

1) Volatile:

A variable should be declared volatile whenever its value could change unexpectedly. In practice, only three types of variables could change:

► Memory-mapped peripheral registers

► Global variables modified by an interrupt service routine

► Global variables within a multi-threaded application

2) Constant:

The addition of a 'const' qualifier indicates that the (relevant part of the) program may not modify the

variable.

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9⟩ Explain Why cannot arrays be passed by values to functions?

Because in C when you say the name of the array it means the address of the first element.

example :

int a[];

func (a);

int func(int a[]);

In this when you call the function by passing the argument a actually &a[0](address of first element) gets passed. Hence it is impossible to pass by value in C.

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11⟩ Explain Scope of static variables?

Static variables can only be accesed in the files were they are declared.

Static variable within the scope of a function store it's values in consecutive calls of that function.

Static functions can only be caled within the file they are defined.

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12⟩ Explain Difference between object oriented and object based languages?

object based languages doesnt support Inheritance where as object oriented supports. c# is a object oriented language because it supports inheritance and asp.net is not a langugae it is a technology

If the language supports ony 3 features i;e (data encapsulation,data abstraction $ polymorphism).then it is said to be object based programming language. If the language supports all the 4 features i;e(encapsulatio,abstraction,polymorphism $ also inheritance )..then it is said to be object oriented programming language.

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15⟩ How to define a structure with bit field members?

You can define structure bit field members with Dot operators.

EXAMPLE:

#include <stdio.h>

int main()

{

Struct bit_field

{

Int x.4; // it allocates only 4 bits to x

Char C.6; // it allocates only 6 bits to C;

};

return 0;

}

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19⟩ Explain Can we have constant volatile variable?

Const and volatile keywords should not be used together because both are opposite in nature.

A variable is declared as "const" means it's value is not able to be changed but if it is declared as "Volatile" then it is not under control.

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