The Sega Digitizer System, a tool used by graphic designers in late 80s/early 90s. According to former Sega graphic designer @AGE43, it was attached to a NEC PC-98 with an HDD. Since the Mega Drive was based on the System 16 arcade board, the Digitizer System could be used with both hardwares. An earlier version was used to develop System 1 games (Pitfall II). At least 3 versions were made: Digitizer System I, II and III.
Some of the games featured above: 1) Pitfall II (Arcade/System 1 - 1985) 2) Fantasy Zone (Arcade/System 16 - 1986) 4-6) Golden Axe II (Mega Drive - 1992)