EMC documentation is emerging

[Fred Proctor <frederick.proctor-at-nist.gov>]

EMC folks,

I wrote up a 6-page description of the lowest level of the EMC software,
the External Interface. This is where the mapping between functions
called by the motion and IO controllers and the actual board functions
(Servo To Go, parallel port) is done. It's an MS-Word file that I'll
convert to PDF soon.

It's on the FTP site (or will be when the auto-copier moves it outside
the firewall), at:

	ftp://ftp.isd.mel.nist.gov/pub/emc/emcsoft/extintf.doc

Comments, please. I plan on gradually documenting my way up to the GUI.

--Fred