Simple question: What is the right most status light for? You have HDD, GDROM, and ??? Is it SCSI transfer? Modem? Also what is that C1/C2 port for? I recall reading a bunch of devices labeled that so I assume it's some kind of controller test port?
I think it's SCSI transfer. The C1/C2 port is for the C1/C2 Checker: https://segaretro.org/File:C1C2Checker_DC.jpg .
