QL-SD ROM (tiny!)

By | 2021-04-29

Hardware revisions

I get asked a lot about the state of my new QL-SD, so here’s an update. The new external QL-SD variant (henceforth called “QL-SD ROM”) went through a lot of revisions:

A sample of QL-SD ROM revisions
A sample of QL-SD ROM revisions

This series also exemplifies my progress as a PCB-designer. I’ve never formally learned to create PCBs, so it’s all learning by doing. With QL-VGA v2 I made my first 4-layer PCB and that experience in turn enabled me to create the final variant on the right, “QL-SD ROM tiny”:

(the case will probably not be part of the final product, but I will offer the files as always).


One of the main features of QL-SD ROM, besides the two MicroSD slots of course, is its 512kB big flash memory. It can hold 8 different QL operating systems (called slot 0 to slot 7) and is bank-switched by software with slot 0 being the default on power up. Switching to another ROM is as easy as entering “ROM_SWITCH 5” into Basic. Also, there is one “Forces ROM 7” switch that can be enabled in case something is wrong with slot 0 so the QL doesn’t boot anymore.

All slots can be re-programmed using a new Basic extension, so updating the QL-SD driver or flashing a new operating system is as easy as typing “ROM_FLASH 2,ram1_minerva_rom” into Basic!

Hardware and software is pretty much finished, so I have sent two units to beta testers and I’m eager to hear what they have to say. When they are satisfied and don’t think major changes are needed a larger batch can be produced.


One of the problems with this new variant is how to get the initial operating systems on it in the first place. It cannot be programmed to the flash before it’s being soldered to the board. One way is to put normal ROM chips into the QL and enable the “Disable OS-ROM” switch on the board. This way the QL boots with the internal ROM and one can load everything needed for the flashing from floppy disc. Afterwards one has to switch it back, remove the ROMs from the QL and test the whole board… this takes a lot of time and I already know that I will loath the process very quickly. So you can see how dedicated I am to producing this by the simple fact that I even developed a special flashing station to bootstrap the process:

The Raspberry Pi’s GPIOs are connected to the QL-SD ROM and then basically emit the same pattern a QL would emit when it flashes the device. I actually had to program the software two times because the first version was written in Python and the Python GPIO libraries are incredibly slow (like “5-10 minutes per board” slow). So I rewrote it in C and that does the whole job within 40 seconds.

But I wanted big SDs!

Yeah sorry, no democracy here. I’m in love with the small form factor and the mechanical stability it provides. I did however buy a cheap MicroSD to SD adapter to test it and it works perfectly fine, so people can still enjoy large SDs with this device. Only one will fit of these as the slots are too near each other, but you can still use the second slot with a MicroSD card.

QL-SD ROM tiny with big SD adapter

What now?

When the tests are finished and everything is alright I’ll have a look at making a first run. I just have one request, please restrain from contacting me personally to be informed when it goes on sale. I’m happy that you are interested but I just get too many requests of this kind. I will publish updates in all relevant channels and this being designed to not be too cumbersome to produce I hope I can make enough for everyone.

27 thoughts on “QL-SD ROM (tiny!)

  1. Jack Gibbons

    Hi this looks a fantastic device and is just what I need for my QL.
    Please keep me posted on your progress.

  2. kleber

    Congratulations.. I am so interesting buy one for my SInclair QL..
    Please, keep me update about the progress, ๐Ÿ™‚

  3. David Westbury

    Excellent, love the dedication to get the hardware just right.

    I’m guessing with a bit of clever code it would be possible to boot straight to SMSQ on GC/SGC (no wait for second boot!).

    Also, it wouldn’t be impossible to implement SMSQ on 68008 QL (with extra RAM) ?

    1. Marcel Post author

      Yes, both things I am thinking about ๐Ÿ˜‰

  4. Mark Stapley

    Will this work in the ICL One Per Desk?

    1. Marcel Post author

      AFAIK the OPD uses a different operating system, so the answer would be no

  5. Marcel Prisi

    Could you please specify what kind of licensing you will use for both hardware and software ? I would love an open-source one.

    And greetings from another Marcel ๐Ÿ™‚

    1. Marcel Post author

      Hey Marcel ๐Ÿ™‚

      Software is open source as always. Hardware and CPLD code is not, sorry.

      1. Marcel Prisi

        Ok, already quite cool to have open-source software. About the hardware, will it be possible to build it for personal use or do you plan on selling it directly ?

        Thanks !

        1. Marcel Post author

          It will probably be sold on SellMyRetro if Rich is interested or another venue willing to do it. But I don’t expect much happening over the summer.

  6. Gregorio

    Fantastic card !!!
    It would be wonderful to have one for my QL, still working, bought in Italy in 1984.
    I hope to read news about its production soon

  7. Ben

    I’d be keen to buy one of these devices to get my ql going again.
    Anything I can do to help your progress?

    1. Marcel Post author

      Only thing that could help is somebody doing the actual manufacturing and stuff ๐Ÿ˜‰

      Maybe I’ll try to get a quote this month, but it’s possible the chips now cost through the roof.

  8. Gary

    This is a wonderful looking project and an amazed at how small and beat it looks.
    You are a genius and really hope that this becomes available to purchase.

    1. Marcel Post author

      Thanks! ๐Ÿ™‚ I have recently updated to PCB to KICAD 6 and made a small change to the CPLD core that I wanted to do for a long time. So a little bit of progress is done. Maybe trying to get a quote, soon, but I fear that the CPLD will be very expensive in current times… ๐Ÿ™

  9. Stรฉphane Pitteloud

    Nice idea, it’s exactly what my QL need to be able to do something with his supergoldcard clone. is it still planned to be out this year?

    1. Marcel Post author

      Yes. Chips are still very expensive, but I did a limited run of 50 boards nonetheless. Still need to cut them up, program then, print an enclosure and then distribute them somehow… just had no time so far.

  10. Doe

    Thanks for this wonderful Job
    When it’s OK , one for my QL !!!!!
    Bets regards

  11. Johnny

    looks very promising ๐Ÿ™‚ please 1 for my QL when you get the time.

  12. Johndoe

    Ce Matรฉriel est parfait pour le QL mais avons nous des nouvelles, ou et quand pourrons nous achter ce produit parfait ??

    1. Marcel Post author

      Sorry, unfortunately I didn’t get any further with it. Somehow lacking the time and motivation to finish it…

      1. medusa

        Oh, pleeeease… it’s exactly what I look for since a few years.
        Think how nice it would be to have a small software toolbox always available on each of my QLs – even the half-disassembled ones or plain motherboards with a keyboard membrane in front of it (you may remember that little monster ๐Ÿ˜‰ )
        I also posted about in the German QL forum…

  13. Johndoe

    Please , please , please Marcel ๐Ÿ™‚ ๐Ÿ™‚ ๐Ÿ™‚ ๐Ÿ™‚

  14. 7alken

    hi, please, can you at least release what you have on github as open hardware?
    I am not old QL user in fact, but got one for some 68k testing and the concept of cheap (edge) 30pin ROM connector usage for writing is interesting also elsewhere using CPLD. I got some info from QL forum how this is done by logic writing through A0-A7 in combination with other A8-A15 at HIGH(?) + /ROMEN … somebody asked if its compatible in all scenarios for QL, this I dont know. As I dont know nothing too how the ROM cartridge is initialized and used in QL, may be you dont have this part completed? Maybe somebody can do it… its interesting project, for sure ๐Ÿ™‚

  15. 7alken

    btw, as I peeked now into QL technical manual, you in fact in case of total replacement of ROMs must REMOVE them from inside of QL? I cant imagine other case … and as cartridge has adresable only 16k $C000-$FFFF you probably must decode the writing also only inside this area, ya? as I sed, its interesting, put it on github at least and hackaday probably, it will be read, just becase of the trick ๐Ÿ™‚


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