In 1999 verscheen er voor de Japanse markt de Nintendo 64 addon 64DD een device die je onder je Nintendo 64 aansloot en dan via een soort van floppy disc een game kon opstarten. Deze flopte keihard en daarom bleef een wereldwijde release uit. Alleen heeft iemand in de US nu een Amerikaanse versie van deze addon gevonden die opstart met de Engelse taal en niet de Japanse zoals normaal gesproken gebeurd. Het hele verhaal daar van kan je hier lezen en een stukje daar uit en enkele foto's hier onder vinden.

Update: Video toegevoegd.

Former Sierra game developer Jason Lindsey took to the Assembler Games forums this week-where you'll find no shortage of classic and rare gaming topics-to show off his latest acquisition. Lindsey told the forum that he had purchased a "prototype for the US version of the 64DD." His attached photos include two screens of the 64DD's boot-up sequence, which normally contains kanji characters asking players to insert a disk; his unit, however, offers those instructions in English.

Further Reading
The fabled SNES-PlayStation prototype has been turned on and disassembled

Prototype plays SNES games, but CD drive is non-functional for now.
The rest of his images reveal hardware that looks mostly like the retail hardware that launched in Japan. The biggest difference is a sticker that labels the system "Nintendo 64 Disk Drive" instead of the final "DD64" name. (Additionally, that sticker is dated 1997, while the final hardware's information stickers were dated 1999.) Lindsey asked for Assembler Games' help to figure out what might be on the blue disk that came with the system, which his English-language 64DD was unable to read. The blue disk color indicates compatibility with the hardware's development units, but its labels and serial numbers didn't hint to it containing anything specific. Collectors will surely hope for a unique game on the disk, as the system only saw nine official pieces of software during its 14 months of Japanese existence, along with dozens more announced games for the add-on that either never came out or were moved to traditional N64 cartridges.