Honestly, this is all a very valid ANSI C discussion, the structures were legal, the bugs more or less obvious... but don't you think that from a '51 standpoint it's all ridiculous? I mean, look, a function that takes a pointer to a structure containing pointer to another structure containing a pointer to a string.. Don't you find this code a bit too complicated for a small 8051? And with so many that simple bugs I honestly advise the thread author: Make it simple! One, two, at most 3 structs per program, no pointers to pointers (except in 2D arrays), otherwise you'll quickly get lost - debugging a program on a microcontroller IS harder than on PC, getting so deep is hardly ever necessary... Maybe if you wrote a TCP stack or something of similar complexity there would be a reason to build so deeply nested structures, but 99% of '51 projects don't need it - and work better without it.

BTW, would someone check what does (corrected)
sprintf(auxBuf,"%c",par->INPS->szInterface);
with structs defined as above compile to? My guess is it's over 100 ASM instructions. Similar thing could be written in ASM in less than 10 instructions...