basics of c and linux internals ,os concepts

They asked about pointers, storage classes, diff between char array and char string, which compiler u r using, memory segments, malloc, calloc, bit manipulations, which controller u used, what processor used in that controller , which architecture it is, watchdog timer, what is volatile, type cast, how to cast int to char, void pointer and why we use it what is stack why we use that rs232,rs485 functionpointers, array of function pointers which debugger u used linked list