Ports and 64-bit Processors

[FreeBSD Questions]

FreeBSD has supported 64-bit architectures for a while now...  Alpha
and UltraSPARC come to mind--even if Alpha is no longer a Tier 1
architecture.  I'm surprised to hear so many of you say that certain
ports are broken on AMD64.  I would think if they worked on other
64-bit processors they'd work on AMD64.  Were the ports that are
broken on AMD64 also broken on those other architectures, too?