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Thread: Recreating the Mindset Keyboard

  1. #1
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    Default Recreating the Mindset Keyboard

    I think I'm gonna put this up into my project list. I've been waiting for years for an M1002 keyboard to come up for sale and they just aren't coming. Worse, I know of a few keyboard collectors who have them, with a couple talking of gutting them for use with a regular PC (sigh).

    Anyway, I don't think this is an impossible project, although lacking a schematic I expect it will be hard. The bitsavers pictures and documentation on the connectors is very helpful. All the parts seem to be available - the only one that is a bit egregious is the MDP1401-223G - only one source I've found, on Ebay, and they want $90 (littlediode). The questions i have to resolve, as I see it are:

    1) How to program a D8749 microcontroller
    2) Is the ALPS keyboard PCB single sided, or are there traces under the keyswitches?
    3) Should I just cannibalize an ALPS PC keyboard for keytops and switches and then make a replacement PCB that matches the Mindset? Or could I figure out how to just take the PCB of an existing keyboard and rejig the connector so that it enables just the keys I require?
    4) Custom keytops to match the Mindset's labelling?
    5) How to make a case for it
    6) How to figure out where traces that are obscured in the lower PCB pictures go (like under the voltage regulator, etc)
    7) Is the lower PCB just doublesided? Or multilayer?
    Figuring out PCB dimensions, etc
    9) Other things I'm not thinking of (probably many)

    Comments? Suggestions?

  2. #2
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    none to spare unfortunately, but I can help with this project. As time allows, working a lot of hours lately.

  3. #3
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    Quote Originally Posted by falter View Post
    Anyway, I don't think this is an impossible project, although lacking a schematic I expect it will be hard.
    There is a netlist, and you have the simulation in MAME so you can determine exactly what the communications protocol
    is. You could probably get more help by contacting Olivier, who wrote the driver. He probably has the microcontroller code
    disassembled.

    If you're really stuck, I have my original circuit tracing scribblings.

    There aren't any exotic parts in the keyboard, that thing you found for $90 is a resistor array.

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    Thanks guys.

    Al - do we need to disassemble the microcontroller code? Is it not possible to reprogram a D8749 with the dump on the bit savers site? I think the rest looks pretty straightforward.. the pics you took are fantastic and look to be fairly dimensionally correct. I think I can take those, convert to grayscale, invert, remove the chips etc and then use that inkscape thing to retrace clean for tone transfer.

    On the lower PCB there are just a few spots in pics that are obscured by things like voltage regulators, white goo, etc. Probably not impossible to sort out. I'm thinking build a wirewrap replica, sort out the missing trace info?

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    Quote Originally Posted by falter View Post
    Al - do we need to disassemble the microcontroller code? Is it not possible to reprogram a D8749 with the dump on the bit savers site?
    Nope, you should be able to just program the microcontroller from the binary.

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    Just for an experiment, I took the bitsavers pic, converted to black and white, inverted it and then used threshold to dial it in a bit... I think I can clean something like this up, remove things that shouldn't be there like wires, etc.. and then retrace it with that Inkscape thing (if I can figure out how to do it myself) so that it is nice and clean.

    https://drive.google.com/file/d/1vbf...ew?usp=sharing

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    Hah, I had no idea Littlediode was still in business/on eBay. I remember laughing at their listings years ago.

    Do yourself a favor and learn an EDA package! It's so much nicer to work with a tool that's meant for the job. I suppose if you're super good with Inkscape, then Inkscape may not feel like a hindrance, but I always hated having to use it for mechanical work (our laser cutter at the makerspace took SVGs, and the makerspace tool of choice was Inkscape, which was OK for artsy jobs). KiCAD is free, stable, and there are a ton of guides in both text and video format for how to get going with it. Plus, if you ever decide to turn your project into a run of boards or just release it or whatever, you've already got a format board houses can talk. And, you can plot to SVG anyway!

  8. #8

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    I second the suggestion to use KiCAD, without a doubt.

    If you have schematics available, and photos / measurements of the real keyboard and PCB, then making a reproduction is very possible. And if there are people who own the keyboard and are willing to give you information, take additional photos and make measurements, etc. then it gets much easier. I'm planning on doing something similar for my HP 2647F terminal that I can't get a keyboard for.

    Just be prepared to learn a lot of skills you may not currently have, and allow yourself the time to learn. If you try to take the "easy way out", i.e. try to use a drawing program instead of EDA software like KiCAD, etc., you will make things much harder than they need to be. Plus, if you do the work and make a good reproduction, you are now in a position to either release the designs as open hardware, and / or sell kits or fully assembled keyboards to others.

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    Quote Originally Posted by matthew180 View Post
    I second the suggestion to use KiCAD, without a doubt.

    If you have schematics available, and photos / measurements of the real keyboard and PCB, then making a reproduction is very possible. And if there are people who own the keyboard and are willing to give you information, take additional photos and make measurements, etc. then it gets much easier. I'm planning on doing something similar for my HP 2647F terminal that I can't get a keyboard for.

    Just be prepared to learn a lot of skills you may not currently have, and allow yourself the time to learn. If you try to take the "easy way out", i.e. try to use a drawing program instead of EDA software like KiCAD, etc., you will make things much harder than they need to be. Plus, if you do the work and make a good reproduction, you are now in a position to either release the designs as open hardware, and / or sell kits or fully assembled keyboards to others.
    There is no schematic unfortunately. Not that I've found.

    I think for my purposes it'll be easier, for me, to work convert the images as best I can of the PCBs that are available and then troubleshoot it from there.

    Another question though.. for the d8749h programming.. it seems people are able to do it with a willem programmer using a slightly modified mcs48 adapter. I can find the adapter no problem.. but when I search for a willem programmer I get an explosion of results, including a GQ-4x4 which I already have. Is what I have considered a Willem?

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    Okay, so I got KiCAD going and, yeah, I think I might be able to make this work.

    What I've done is I've taken the pics of the Mindset boards, converted them into black and white as above. Then what I've attempted, and seems to work, is importing them as BMP files into MOD files in Kicad, with the intent of using them as templates to trace over. That *seems* to work, and I can remove the 'template' after. So I start from the top with a MOD of the image of the top of PCB, trace that, then delete that MOD, and then overlay the bottom (which would have to be flipped, obviously) and then trace over that with the second layer tracks.

    I've got two questions for those in the know:

    1) When you are laying tracks, do you lay them just to the edge of the pads for each DIP socket? Or do you go right to the center (the hole)? I'm assuming to the edge.
    2) DIP socket MODs are presumed to be 'double sided', right, since they're through plate (at least, that's what the ones I'm picking suggest they are)
    3) For historical purposes, I'd like to keep the fancy grid design around the edges of the bottom of the controller PCB. See how it has those thick traces and wide corners? I can do the thick traces and create the same 'grid' pattern it has, but the corners vex me. If you think of a corner as a triangle, I can make the traces nice and thick and meet at a corner, but I cannnot create a third side and fill in the whole triangle. Is this accomplished some other way, like graphics?

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