In 1998, the MMC Association underwent a mysterious split, leading to the creation of the SD Association in 1999. The origins of MMC are shrouded in uncertainty, with limited information available from questionable sources like blog posts and articles. Interestingly, the development of MMC involved companies like SanDisk and Siemens, with historical oddities like ROM-based MMCs being used in select devices. The article delves into the details of MMC and SD standards, including security features like DRM on flash cards and the development of SecureMMC. Despite some controversies and unusual developments, SD ultimately emerged as the dominant storage standard due to its focus on practicality and user-friendly approach.
https://sdomi.pl/weblog/21-nobody-knows-what-happened-at-mmca/