I'm not entirely sure but if memory serves me well this program was the one who got my interest in computer chess started. Update: the brother of my chess-friend confirmed that it was indeed Ultra chess!
Using the OpenMSX MSX emulator I let POS 1.6 (development version) play a game against Ultra Chess. The logfile (with the moves played) can be found here.
Logfile of Pos 1.19 versus Ultra Chess can be found here, the pgn-file can be retrieved from here.
Ultra chess was published for MSX computers (MSX-1 with 64KB of RAM) by Aackosoft in 1985 on a cassete.
I'm hoping that one day I'll find an original Ultra chess ROM cassette for that retro-feeling. If my MSX no longer works, I might buy a One Chip MSX.
I started collecting chess programs. My collection can be found here.