Details of hardware, software and manuals are available here: https://www.dropbox.com/sh/ezzga2dppm6jlm7/AACwFC_rv2QatWh_ndKc9fhma?dl=0
The board allows for 5v TTL serial output and connection to a USB SD card module as well as a ESP8266 WIFI module. The board has been used for many purposes including running games from SD Card, MIDI, RS232 and accessing online BBS.