Yes it is the correct keypad, I was just teasing you with that wink that I know you took the artwork from JKCEMU.
http://www.jens-mueller.org/jkcemu/lc80.html
http://www.jens-mueller.org/jkcemu/poly880.html

SC1 is "SC1" because the file is "sc1.rom", it was not MAME who named it that. Here's a forum thread also mentioning it:
https://www.robotrontechnik.de/html/...threadid=16069
"Hier handelt es sich um das auf den Poly880 angepasste Schachprogram vom SLC1 (Schach- und Lerncomputer), nicht zu verwechseln mit Schachcomputer SC1"