Posted by Dudah on 7, 2001 at 8:07 PM:
I found this while catching back up with the game boy development scene. Looks like some sort of hookup to a board and a monitor. Anyone speak japanese? According to him, it's a arcade PCB control box.
http://lillith.sk.tsukuba.ac.jp/~kashima/games/cbox/cbox.html
-Kev