Description and purpose of the “M4 board”. The M4 board, features as previously described a ST32F407 Cortex M4 MCU, connected via SPI to a ESP8266 WIFI module, and 18 GPIO’s routed via a GTL2000 voltage translator chip. It was meant to be connected to the old the Amstrad CPC (z80 based) computer via it’s expansion … Continue reading M4 Board – Retrofun, 8-Bit Amstrad CPC WiFi