Another board I started a long time ago, but due to time/life, has been on the shelf.

M7 board is connected between a Z80 and it’s dil socket.

For starters aimed at the Amstrad GX4000 console (and of course the other Amstrads), boosting it to be a full blown CPC+ computer. But maybe later other Z80 based computers.

It gives similar features of M4 board ie.:

WiFi abilities

SD card as mass storage

Rom board

Cartridge emulation

and much more.

However due to the design it will be able to offer more than the M4 board.

The Z80 datalines can be intercepted, so technically any hardware can be emulated on the Cortex M7 chip (disc drives, tapes, keyboard), providing the Cortex-M7 can keep up.

The design is:

STM32F7 mcu handling the Z80 address, data and control lines, SD card.

STM32F1 mcu being USB host, interconnected to the Cortex-M7, via 8 datalines and 4 address lines (covering the keyboard matrix).

ESP8266 handling the WiFi, connected via SPI to the Cortex-M7

Level converter between Z80 datalines to STM32F7 with OE signal

And a bus switch to seperate the Z80 datalines from the motherboard, this way any response on an I/O port for example can be “replaced”.

Planned features for starters is, expanding ram, probably I will spare 256KB + the internal 64 KB for starters.

Add key+mouse option (via ie. logitech unified) through the USB socket.



Debugging signals on a CPC464 and physical layout.







Basics working on a Amstrad GX4000 console.

More to come when time allows.