The MechBoard64

 

 

Shift Lock Circuit

The original Shift Lock key uses a latching/locking type switch. Cherry used to make these but have since discontinued making them. Thus, I had to come up with another solution. I therefore made a small circuit which adds a push on push off functionality. This way a standard non-latching microswitch can be used to turn on the Shift Lock and when pressed again, turn it off. In order to get a visual indication of the state of the switch (on or off) a red 3 mm LED is placed underneath the keycap which lights up whenever the switch is activated. The circuit is made from a few standard components including a NE555 timer, a 4066 analog switch, some resistors and two capacitors.

Before transferring the circuit onto the PCB, the Shift Lock circuit was tested with a simple breadboard connected to a Commodore 64. The Shift Lock circuit is powered using the 5V line going to the keyboard. This 5V line is not used on the original C64 keyboards, so it came in handy for powering the Shift Lock circuit on my keyboards. The 5V line is also present on the C64 Reloaded boards and Gideon has confirmed that it is also present on his Ultimate64 boards (thanks Gideon!).

Two SIP sockets have been added to the Shift Lock microswitch. This way the color of the 3mm LED can easily be exchanged to match the color of the power LED of the machine.

It is also possible to exchange the standard non-latching microswitch with a locking type switch like the Cherry Locking switch. To do this, the momentary microswitch obviously needs to be de-soldered and replaced. In that case the small Shift Lock circuit is no longer needed and must be bypassed in order for the locking switch to work properly. This is simply done by moving the two header caps inside the Shift Lock Circuit area of the PCB as indicated by the text on the board. Easy peasy!

NOTE: Using the MechBoard64 with a Keyrah from Individual Computers (link) should be possible. However, as the 5V line of the Keyrah is not connected, neither the Shift Lock circuit nor the LED will function. In this case, a Cherry Locking switch may be used instead.

Wiring the MechBoard64

The keyboard is connected to the motherboard using a 20 cm ribbon cable. Below are images from installation in a long board (Assy 250425) and a short board (Assy 250469).

One of my C64C slim cases has an Assy 250466 long board installed as Commodore basically assembled machines depending on what they had in stock. The combination of a long board and a C64C slim case places the keyboard pins on the C64 motherboard quite far from the keyboard pins on the PCB and the 20 cm ribbon cable is simply too short. I therefore had to use a 10 cm extension cable to make it work. I have also seen Assy 250425 long boards installed in C64C slim cases. That combination will also need an extension cable…

Keyboard Case & Mount Compatibility

I wanted to make sure that the keyboard is as universal as possible. I therefore tested it in all the different machines that I have in my possession. I found that the MechBoard64 fits perfectly in all of my machines regardless of the internal hardware and cases (breadbox and C64C slim cases). The only combination that caused some trouble was long boards (e.g. Assy 250425 and Assy 250466) installed in a C64C slim case. This combination needs a longer ribbon cable in order to make the connection as described previously!

Adding the MechBoard64 to Real Hardware

Well, there is not much to report as the MechBoard64 simply does what it is supposed to do – give inputs to the Commodore 64 regardless of motherboard version. The Shift Lock circuit works like a charm and turns on and off as it is supposed to. The MechBoard64 fits perfectly in both C64C slim cases and the old breadbox cases.

If looking closely at the images below of the keyboard inside a C64C case, it’s possible to see the wider Gateron microswitches underneath the keycaps. This is of course not possible on the old keyboard as it has, well no microswitches. All that is visible is the springs…

…and after waiting for more than two years, my C64 Reloaded machines have finally gotten their new keyboards… Now I just need need some keycaps. Please hurry up Phase5!

Final Thoughts

My little keyboard project has finally come to an end! I’ve spend 350+ hours on the project and the total cost of making the two keyboards exceeds reason by a very large margin… But it has been sooo much fun creating something usefull for my machines that I couldn’t just order somewhere. Hopefully they will last for at least 30 years! The final looks of the keyboard also exceeded my expectations by far and I’m really glad I abandoned the acrylic plate bracket and went for an aluminum version instead. The final version is very stiff and should be able to take some serious pounding…

© breadbox64.com 2018

11 comments on “The MechBoard64

  1. 3D printed ketycaps would definately work. However, the finish will be different compared to plastic molded keycaps 🙂

  2. so.. basically… that’s the final stage in reproducing new c64’s.
    take a new c64c case from icomp, take the ultimate64-II mainboard (as the one icomp offers still needs the old chips you can’t buy anywhere), take that white psu boxy thing made by yet another company and take this keyboard… and you have a complete brand new c64. Btw scr** the ‘original’ keycaps. Why not just take any keycap that was designed for these switches and already is mass produced and just have the commodore pictures lasered onto them instead. Same mold, for all I care even the same grey plastic, just different images on the keys 😉 (or would normal keycaps be too low to come out of the case or something)
    Now all that’s needed is a shop that sells it all in masses, in one place. Preferably already assembled and put into one box 😛 (the keyboard has been the ‘missing part’ for years now, all of those chips have had fgpa replacements for ages. The case molds popped up again, nobody even wants the original PSU as it’s a death trap so there are at least 3 better mass produced replacements for those on the market. But nobody ever came up with a keyboard to complete the thing.

  3. If the ultimate goal here is ultimately completely new machines with completely new parts, then the need for keycap adapters and old keycaps may not be ideal for achieving it. Doubleshot PBT keycaps are really expensive, but UV printed keys are pretty attainable in small, even single-unit quantities. The question is … will standard keycaps even fit the C64 housings?

  4. I would love to be able to use a Commodore 64, built brand new from new parts like this as a daily driver for work. Maybe if someone can develop GEOS 3.0 and develop enhancements to the GUI for daily use…
    We can deal with the graphics not being the best, but memory, disk speed and networking would be a problem – so you should consider increasing the RAM (as if you had a expansion module built in) – include a SD Card reader in the side somewhere, so we can use SD Cards like small floppies and give me an Ethernet port or wireless so I can actually send an email.
    I believe all of these things have already been developed – either here or by others working on different projects.
    You should start a manufacturing collective, gathering parts from all the other projects out there and assembling them here into a kick ass C64R (R for Reloaded)… Use the newer C64c style case, it looks better than the breadbin – dare I say it.

  5. Have you considered releasing a variant of the MechBoard64 which works as a USB keyboard? It would be a good complement to both software emulation running on modern PCs and … certain hardware C64 replicas which use USB keyboards. An integrated dual USB hub would be ideal, as that would allow joysticks, USB drives, SD2IECs, and also mice and normal PC-layout keyboards to be plugged in.

  6. Hi Leo, I have actually played around with the idea of implementing a small circuit that would enable USB connectivity. To keep the MechBoard64 in its current form, I think the best approach would be in the form of e.g. a cheap daughterboard that can be inserted directly onto one of the 20 pin male connectors. It could also be one of the smaller (and cheaper) Arduinos with USB integrated. The latter doesn’t have the USB hub you talk about. However, having a readily programmable platform will certainly make things happen a lot faster in comparison to developing a new PCB 🙂

  7. What an amazing build! Are the new C64 to MX adapter .stl files that you improved available to download at all?

  8. Hi Patrick, I did not alter the orignal .stl that much. I basically filled the top right hole with a logo plate 🙂

  9. Just wanted to say I’m really interested in this product as I am going to build a new C64 soon. Looks fantastic!

  10. Is there gonna be a 128 version of this? I have a 128 that needs this due to a sticky “,” key 🙂

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