Recently I had the fortune of obtaining this this old video game system. It came with the NEC pack (PAC-N1) to play PC-Engine games and the SEGA pack (PAC-S1) for Sega CD and Mega Drive games.
The last thing to check was the Sega pack (PAC-S1). I inserted the pack into the system and when I turned it on, I would only get some green lines on the screen. I thought it was dead but then a very nice ebayer with the ID of maestroaxeman contacted me and told me something very important. It turns out that the games have to be inserted upside down! After I tried that tip, the games worked perfectly!