As a child, I had a variety of chess programs on hardware ranging from Atari, Amiga, and Windows PC. I played them against each other regularly – in tournaments and in “championship” matches. I recorded everything and even tried to approximate their Elo ratings. Yes, I was a little geeky…back then.
All the moves had to be entered by hand on my part from one program to the other. Of course if I had a setup like this, it would have been a lot more fun.