Perl is a Turing complete language, so anything that is computable can be computed in Perl as well.
If you are willing to wait an infinite amount of time, expend an infinite amount of memory, and restrict your I/O needs to nothing more complex than an infinitely erasable paper tape, then, yes, Perl can "compute anything". That's a rather limited view of "anything", in my opinion. :-)
In the real world, we have real-time applications; Turing-completeness cannot speak to such requirements. Similarly, when trying to access memory mapped I/O, Perl has no native facility that I know of to write to specific memory locations; whereas other languages do. (Even BASIC has it's PEEK and POKE statements!) In Perl, we fall back to using C via XS instead; there is no native "POKE" statement, though unpack with pointers can be used to emulate a "PEEK".
Unless I'm mistaken, this is something that native Perl can't do.