@440bx : A real extended is 80 bit default on 32 bit, but only 64 bit on x86_64, but:
That limitation is technically only for window x86_64 due to Win64 ABI limitations on win64. E.g. Linux x86_64 can be compiled to use the fpu unit and so can ( not default) support 80 bit. You need to compile the compiler yourself to have that feature. Anyway really high precision (much better than 80 bit) is available in software at an additional speed cost. And the x87 FPU feature on x86_64 is also kind of slow.
Not quite correct: all x86_64 targets
except Win64 have
Extended enabled by default. Only for Win64 one must enable it by recompiling the compiler with
FPC_SUPPORT_X87_TYPES_ON_WIN64 (see
compiler/x86_64/symcpu.pas, line 181 and
compiler/psystem.pas, line 314) - of course the remainder of the FPC distribution needs to be compiled then as well.