The RVT-R Writer is a Matshita SW-9585-C DVD-RAM drive with firmware developed by NEC. These drives show up as SW-9585-S drives when connected to a computer, although the "-S" model number was not specific to Nintendo's drives.
The large enclosure is a simple IDE-USB adapter with built-in power circuitry. The drive is capable of reading all normal DVDs, along with RVT-R discs. Even in stock configuration, the drive can be recognized by Windows and RVT-R discs can be dumped using Imgburn.
Drives use a fixed VID and PID for identification with the software.