binary compat guarantees ?

aix / solaris are no different in that respect.

64bit new stuff will NOT run on 32 bit old stuff.

32bit old stuff will run on 64 bit stuff.

device drivers, X11 extensions, kernel extensions, they will NOT run on new stuff ( AIX or Solaris )

tried that, got the T-shirt, works as promised ( NOT )

compat guarantee is there for AIX, just like for Solaris.

the link is here, if you care for it.

http://www-03.ibm.com/servers/aix/os/compatibility/

btw, AIX 5.2 also supports power6.

now, compare that to sol8 on niagara.