Butenko was simply the most capable programmer that I've ever worked with. He was also very accomplished. I'm sure everyone has an idea what UNIX v7 was. Although BSD, sockets, and VFS were still in the future, it was a sophisticated OS for its time. Butenko wrote his own OS that was about a peer for the v7 in features (including vi). He also wrote a Fortran 77 compiler with IDE, an SQL database, and a myriad other things. Applications, too: games, communications, industrial control.
I still remember one of our first meetings in the late 1983. I wanted someone to explain me the instruction set of Mitra-15, a French 16-bit mini. Documentation was practically impossible to get back then, especially for undergrads. Someone referred me, and I received a lecture at a smoking area near an elevator, which founded my understanding of computer architecture.
The only time I ever got one up, was when I wrote a utility to monitor processes (years later, top(1) does the same thing). Apparently the concept never occurred to Butenko, who was perfectly capable to analyzing the system with a debugger and profiler. Seeing just my UI, he knocked out a clone in a couple of days. Of course, it was superior in every respect.
Butenko worked a lot. The combination of genius and workaholic was unstoppable. Or maybe they were sides of the same coin.
Unfortunately, Butenko was not in with the open source. He used to post to Usenet, lampooning and dismissing Linux. I suspect once you can code your own Linux any time you want, your perspective changes a bit. This was a part of the way we drifted apart later on. I was plugging on my little corner of Linux, while Butenko was somewhere out in the larger world, revolutionizing computer-intermediated communications.
He died suddenly, from a heart failure. Way too early, I think.