A candid photo of Don Killen back in his younger days. I received a sad email from Andy Johnson of Greenleaf Software yesterday, giving me the news that Greenleaf’s founder Don Killen died in his sleep Monday, August 21, 2006.

Don was a pioneer in the world of desktop C and C++ programming, since he sat down in 1982 and hammered out his flagship product, Greenleaf Functions. Back in the days when MS-DOS programmers still had to use the Lattice C compiler, Don saw that there was potential big market for a library that provide glue between the BIOS, the DOS API, and C programmers. Armed with references and a copy of MASM, he created the product, placed a few ads, and found himself with enough orders to go into the business full time. (Mind you, this was back in the early 80s, and Don was managing to get over $200 a pop for this library.) You can follow Don’s version of that history here .

I went to work for Greenleaf in 1989 after burning most of my bridges with telephony startup SRX (later absorbed by Teltronics .) It was a big change for me - Greenleaf was a small family business and I had to try to learn how to operate in that kind of environment. During all my years with Greenleaf, I could never forget that it was Don’s world, and we were lucky to get to play in it.

Greenleaf had quite a few good years, but as the 90s waxed the product mix wasn’t attracting the kind of sales that it needed to keep the place going, and Don’s health was always an issue. Despite a fortunate kidney transplant, as he got older, I don’t think he had the energy and vigor he needed to reinvent the company for the new millenium. Seeing the writing on the wall, the development team branched off to form a contract programming company called Addisoft Consulting. Tammie Williams, Patrick Little and Ruby Hjelte are still there, and worked with Don and Greenleaf from time to time.

Working with Don was a great experience, and I can honestly say that I learned more about the software business from both him and Tammie than I could have managed anywhere else. It was a rare opportunity for an inexperienced programmer, and I really feel luck to have had the opportunity, and to have gotten to know Don.

May he rest in peace.