Okay, here is my take on this issue:
The GPL requires the sources be available:
b) Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange;
Seems to me that in 1997, the Internet would qualify as "a medium
customarily used for software interchange." Stick it on an FTP site
and leave it there for three years. Make a one-line note in your
manual saying "The source code for [some of] the control software used
in this product is available from ftp://ftp.bigcompany.com/foo/bar/baz".
There. Done.
-hpa
-- PGP: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD 1E DF FE 69 EE 35 BD 74 See http://www.zytor.com/~hpa/ for web page and full PGP public key I am Bahá'í -- ask me about it or see http://www.bahai.org/ "To love another person is to see the face of God." -- Les Misérables