6.2-n32 was compiled  on a R10k with -n32 -mips3 flag. (should 
        run on 6.2 R4400 machine with -n32)
 6.2-64bit compiled on a R10k with -64 -mips4 flag

 6.5-n32 was compiled on a R5k with -n32 -mips3 flag

 If you don't know what -64 and -n32 are or if you're not specifically 
 looking for optimized performace, you should get the 32bit version
 that matches your OS version.

 For Irix later than 6.2, -n32 version probably works better.