Extra words

The Core words (B420) section contains the absolute minimum
needed to get a usable Forth interpreter with input buffer and
disk blocks access running. The goal here is to minimize the
binary size of a minimum Collapse OS install.

Extra words are words you will most likely want because they
are generally useful. They are so useful that they are part
of the Dictionary (B30).

Some programs need them, so they will automatically LOAD them.
To that end, the loader is conditional: it aborts if extra
words are already present. Load with "152 LOAD".
