The Universal Serial Interface for Amstrad CPC (USIfAC), currently in version 2 (Styled USIfAC II), is a modern serial interface based around a PIC microcontroller designed and built by ikonsgr from the CPCWIKI Forums.The only chip on the board is the 18F47Q10 PIC. The PIC software is written in Great Cow Basic and has been released by ikonsgr. The board allows for TTL serial output and connection to a USB Stick as well as a ESP8266 WIFI module. The board has been used for many purposes including running games from Usb Stick, MIDI, RS232 and accessing online BBS.
Project's Main Thread:- https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/usifac-iimake-your-pc-or-usb-stick-an-hdd-for-amstrad-access-dsk-and-many-more!/
Special thread for technical problems & support: https://www.cpcwiki.eu/forum/hardware-related/usifac-ii-technical-problems-support/
Details of hardware, software and manuals are available here: https://www.dropbox.com/sh/ezzga2dppm6jlm7/AACwFC_rv2QatWh_ndKc9fhma?dl=0
Useful links about USIfAC II:
A small Basic utility for easily mounting dsk images to the 4 image slots: https://www.cpcwiki.eu/forum/index.php?msg=200760
Some stuff about linux & python: https://www.cpcwiki.eu/forum/index.php?msg=201894
3d case: https://www.cpcwiki.eu/forum/index.php?msg=207446
Usifac II schematics & raster implementation:https://www.cpcwiki.eu/forum/index.php?msg=212833
Simple way to detect USIfAC II: https://www.cpcwiki.eu/forum/index.php?msg=213269
Load CPM PLUS for USIfAC II (mass storage support): https://www.cpcwiki.eu/forum/applications/hdcpm-boot-and-run-cpm-plus-from-hard-disk/