The DB unit in the 32-bit version has some examples of how it's done in general.
Basically, in 32-bit mode a DLL is mapped into each process's address space, not an
address space of its own, so that it cannot share memory simply by virtue of being a DLL.
You must use some kind of shared memory object -- such as shared memory, or a
memory-mapped file -- and employ semaphores to properly synchronize access to it.