Question:

When I run ttgrid, it runs fine while iterating through the depths, but then goes completely ballistic, spewing out strange characters.

Answer:

ttgrid writes the binary output file to stdout; you must redirect the output to the right file, eg:

% ttgrid db > ttgrid

The command line versions of dbsort, dbjoin, and dbsubset also write binary output files to stdout. Generally, your xterm or command tool window won't like that.