How to run oracle 10gR1 on tiger ?

Installing oracle 10gR1 on tiger is not supported by oracle. It also is not very straight forward but ... it is possible.
Just install the software as you did with macos 10.3.
make sure you have gcc 3.3 as default compiler, set this as default by running the command "sudo gcc_select 3.3"
cd $ORACLE_HOME/lib
mv libnnz10.dylib libnnz10.dylib.ori
relink all
mv libnnz10.dylib.ori libnnz10.dylib

When you have gcc 4 as default there will be quite a load of errors and no results.

now you can run dbca and create a database

Ronald.