Hi, is exception handling relevant to C51(like try-catch)?
No: C51 is an ANSI 'C' compiler - not C++!
I seem to recall that Ceibo makes a C++ compiler for the 8051. There's also the Comeau compiler, which compiles to C to be compiled by someone else, but Keil isn't one of their official target compilers. I'm not sure how 8051-friendly their C would be.