Then, it's a matter of adding layer after layer. For most
system, all those layers except the drivers will be added the
same way. Drivers are a bit tricker and machine specific. I
can't help you there, you'll have to use your wits.

After we've loaded the high part of the core words, we're at
the "wrapping up" part. We add what we call a "hook word" (an
empty word with a single letter name) which doesn't cost us
much and can be very useful if we need to augment the binary
with more words, and at that point we have our future boot
CURRENT, which PC yields. That is why we write it to the
LATEST field of the stable ABI: This value will be used at
boot.


                                                        (cont.)