"GRETA is supposed to expand an Amiga 500 by 8 MB SDRAM, an ethernet controller as well as a port for MicroSD cards and a freely usable I/O-port. It seems that the development of the board has been finished but since 2013 obviously the programming of the FPGA was not continued: Currently GRETA only offers additional memory. All other features still have to be programmed. The documentation of the projects are available on Github under the GNU General Public License."

http://www.amiga-news.de/en/news/AN-2016-04-00050-EN.html