On Oct 9, 2013, at 12:55 AM, "Brian Fay" <ovaltinevortex@gmail.com> wrote:

I have a copy of the book checked out from the library. It's a really great intro to writing externals, although a solid understanding of C is really required to understand the book.

The book unfortunately seems to be out of print, but I'd expect that Max/MSP would have some helpful documentation for writing externals. The process in Pd is very similar.
I thank Brian for his kind words about my book. The book also contains an excellent chapter by Miller on his philosophy of writing externals that may be of interest to readers of this list. The book is still in print, and can be purchased directly from A-R Editions over here : https://www.areditions.com/cmdas/DAS25/cmdas025.html. Please contact me off-list if you would like to purchase the book but run into difficulties.

Thanks,

Eric