Deunan, the developer of the Dreamcast emulator, Makaron, began a project titled GDEMU, in private, in 2008. On August 7, 2011, it was first announced to the public. The GDEMU is a custom-made board that emulates the board controlling the GD-ROM drive, allowing games to be run from an SD card, rather than on GD-ROM or CD-ROM. By the fifth revision of the board, Deunan decided that the device was ready for production and began taking pre-orders on March 31, 2014. The first batch of units was announced as shipped on April 9, 2014.
The upside to this method of reading SD cards, as opposed to the earlier SD adapters that used the serial port, is that performance is equal to or greater than when using optical media.