M7 / Galaxy Board

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.

26 thoughts on “M7 / Galaxy Board”

  1. Hello,
    I am interested in buying an M4 plate for my Amstrad CPC 6128. Could you tell me how to make the purchase, make the payment, the price of the M4 and the postage for Spain ?. Thanks and best regards.

    Fco. Javier Haro Herreros

    1. Hi Duke,

      I would Like to purchase a m4 for my 6128 plus. It looks fantastic!
      Please could you contact me.

  2. Hi Duke

    Loving the idea of your M7/Galaxy board!
    I would love one for my 6128 when you get there.
    As you said you were starting with the GX4000, I’ll probably have to try to grab myself a GX4000 just to use one of your M7/Galaxy boards on it!

    Great work, Duke!

    1. Hi Rhinoman,

      Thanks 🙂

      Actually the base version intended for GX4000, would work on any CPC, however due to physical changes on the various CPC motherboards, the board will simply not fit all, ie. CPC 464/6128+ it would not be able to fit because the cartridge connector is in the way, the PCB would need to be mirrored to fit those. I haven’t check all the different PCB revisions yet, but no doubt many it will fit as it, others it wont, and a re-layout will be needed.
      However, I have plans for an external version too with 8MB ram, but more about that later 🙂
      Hopefully I can soon make an update on the progress.


  3. Hi Duke,
    This is just an awesome project keep up the hard work. Also if there is a pre-order/mailing list for M7 boards I’d appreciate you sticking me on it. Many thanks.

    1. Hi Psychofox,

      Thanks 🙂 – I don’t take any preorders yet, right now have a little summer break from the project..

  4. Hi there Duke.

    Amazing project. I’d like to get the M7 board. I’m really happy with the M4 but the extra RAM is what I need to make SymbOS work at full capabilities.

    Hope to hear from you soon.

  5. Dude, you are making my dream come true!
    My little 6128 would fly with this board and SymbOS!
    Keep up the great work!
    Can’t wait to buy it 🙂

  6. Hi Duke,
    I would like to purchase M4 for my 6128 plus.
    How and where to buy it?


    1. Not possible with the current board. It could become possible, but it would be a lot of work, basically keeping track of all CRTC, GA registers and ram contents, to render the image.

  7. Hi Duke

    I was wondering how you’re getting on with the project?

    I’ve recently rediscovered the GX400 after seeing game reviews in Mean Machines Magazine in the UK as a child (I had a NES at the time). I have purchased a multicart for my GX4000, but this blows my mind!

    Will you be posting on your blog when you’re ready to take pre-orders?

    All the best

    1. Hi David,

      Tbh. I have not worked on this project for quite a while. I hope to pick it up again soon(tm).
      I will post progress then.



  8. Hello Duke.
    I’m very much interested on the M4 board for my CPC6128. I would also like to purchase the M7 when ready. I design controllers on Cortex-M4 & M7 and your site was a very pleasant surprise for me. Congratulations. Please advice on how I could possibly purchase the M4 Board for CPC6128. Thank you very much.
    John, Athens, Greece

  9. Bonjour , et merci pour ce que vous faites , j aimerais beaucoup vous commandez la carte m4 board et votre futur carte M7 , merci

  10. Hi Duke,

    I just want to thank you for your superb work on the M4 Board. It is truly a must-buy for anyone that has an Amstrad CPC machine. There is nothing quite like it: mass storage, Wi-Fi, .dsk support, NMI… It’s simply a fabulous device!

    I’m looking forward for the M7 Board for the Amstrad GX4000 and I’m sure it will be the best expansion board for an Amstrad machine ever. I’ve already bought a GX4000, just in case the M7 Board becomes avaliable some time soon.


    1. Thanks. I am happy to hear that 🙂

      The M7 board is not in active development at the moment.
      Maybe I pick it up again someday.

  11. Hi Duke,

    Any news on further development on the galaxy board. I love your m4 and use them almost daily, but my gx4000 needs some love!


    1. Hi Craig,

      Glad to hear you are still happy with the M4 board.
      I haven’t really worked on the Galaxy board for a long time, real life and half the weekends spent building M4 boards & Imperium Solo’s got me caught up. Maybe in the new year!


  12. Hello Duke,
    I would like to buy another M4 board for my CPC 464, Is that still possible?
    Best regards

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