64DD

The is a peripheral developed by Nintendo to expand the capabilities of the Nintendo 64 with rewritable magnetic disks and online connectivity. Announced in 1995 before the Nintendo 64's 1996 launch, it faced multiple delays before its release in Japan on December 11, 1999. The "64" references both the Nintendo 64 console and the 64 MB storage capacity of the disks, while "DD" stands for "disk drive" or "dynamic drive". Despite its innovative features, it struggled to gain traction and was discontinued after a short-lived run in Japan.

Plugging into the extension port on the console's underside, the 64DD enabled expanded, rewritable data storage via proprietary 64 MB magnetic disks. It introduced a real-time clock for persistent game world elements and included a standardized font and audio library to optimize storage efficiency. Its games and hardware accessories allowed users to create movies, characters, and animations for use across various titles and shared online. The system could connect to the Internet via a dedicated online service, Randnet, which supported e-commerce, online gaming, and media sharing. Described as "the first writable bulk data storage device for a modern video game console", Nintendo envisioned the 64DD as an enabling technology for pioneering new game genres and applications, though many of these remained in development for years and never saw full realization.