It does look extremely similar to an SD card in construction, with a large flash...

userbinator on June 3, 2017 | parent | context | favorite | on: Reverse engineering a Nintendo Switch cartridge

It does look extremely similar to an SD card in construction, with a large flash die and a smaller controller: https://www.bunniestudios.com/blog/?page_id=1022

The part number on the IC, after some contrast enhancements, appears to be MX28K128GL0 --- not a publicly documented Macronix part number, but may be related to the 28F128, a common 16MB (128Mb) NOR flash.

consp on June 3, 2017 [–]

Considering the download size of the games, a 16GB (128Gbit) chip is more likely