This is Sega's official Development System for the Dreamcast. Code named 'Katana' (early models of this actually said Katana in place of the Dreamcast name/logo). It's a complete hardware Dreamcast emulator that is connected to a PC via a SCSI connector and can run any game code you load onto it.

This is the Katana GD-ROM Writer. This can burn special 'CD-Rs' that will play directly in system above.