While I haven't written it up anywhere, it's also fun to point out that I've had success talking to a Seagate drive by wiring the debug port directly to the TTL

While I haven't written it up anywhere, it's also fun to point out that I've had success talking to a Seagate drive by wiring the debug port directly to the TTL serial pins on the debug header of a Linksys WRT54G router.