#define MICHAELSINTVECTOR 13 /* = (0x6b-0x03)/0x08

In Keil, there would be no point in manually doing the calculation like this to get the magic number 13; you would simply write

#define MICHAELSINTVECTOR (0x6b-0x03)/0x08

and the compiler does the calculation at compile time (and hopefully comment all those other Magic Numbers!)

Is this not the case with SDCC?

BTW: Note that your definition has an unterminated comment - never have an unterminated cpmment (including a C++ style // comment) on the end of a #define... :-0