For anyone who wants the source code to MegaTerm, I have put it online.
You can get it from my home page, at http://www.xmission.com/~redflame
(it is the last link in the menu).

MegaTerm is a graphical term program for the Apple //gs that emulated
ANSI "graphics".  It was fast enough to handle about 2400 baud on an
unaccelerated //gs (which was good since 2400 baud is what my modem was
hehe).

It's all written in assembly language.  There is a short tutorial
explaining how to assemble it.  It was assembled using Merlin 16 (and
fortunately I found my original disks for Merlin a few days ago, which was
a good find since the only thing I could find on Asimov was a Dos 3.3
version).