You can read more about it at http://www.spinpoint.org/cpc/m4info.txt and at https://www.spinpoint.org/2019/11/19/m4-board-guides/
<gallery>[[Media:Amstrad CPC M4 Board Extended User Manual.pdf|M4 Board Extended User Manual]] [[File:M4board_front.png|500px|M4 Front View]] [[File:M4board_back.png|500px|M4 Back View</gallery>]]
== Firmware ==