[ale] Rolling your own terminal emulator

[lists at sourceillustrated.com (John Wells)]

Guys,

We have a need to heavily modify a java terminal emulator.  While I
understand the GUI-specific code itself very well, I need to gain a better
understanding of the terminal code.

I'm looking for a tutorial/document/book/site that describes how to write
a simple (or optionally complex) terminal emulator.  I understand it's
really just buffering input, sending across the wire, echoing characters
properly, etc, but there's also control characters to handle, positions to
write on the screen, and other items that are a bit more obscure as far as
I know.

If you were to write your own terminal emulator, where would you begin? 
What are the steps to terminal enlightenment?

Thanks for the help, as always.

John