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Universal Retro keyboard

Posted: Tue Jun 25, 2019 7:47 pm
by dave
Now that we have Klyball's 542C recreation in addition to the original 542 recreation keyboard, there's not much of a void in the OSI keyboard area anymore. But, many of us also have other vintage machines that use ASCII keyboards. For that matter, so did the older OSI machines.

I've been meaning to put together a (semi) universal ASCII keyboard for vintage computers. I decided to use KiCad rather than my tried and true Altium so that the result would be available to be modified by anyone. Last night, I bit the bullet and plowed through the KiCad learning curve, and managed to get the first cut, which I have on GitHub.

The first cut is basically an OSI 542 vanilla polled keyboard, but I've replaced the 8T26's with a pair of 74LS240's, and the 7475's with a 74LS373. (HC parts will fine as well). I've left room to escape the connector to a blank area of the board, which can be used for extra functions such as:
  • Module to provide advanced features of 542B/C, which can also be added to stock 542 keyboards (compatible with 16-pin header)
  • Shift-lock emulation
  • ASCII keyboard emulation with parallel out
  • Different polled keyboard emulation (using a 2-port RAM)
  • Serial keyboard emulation with PS/2 or USB interface
It so happens the dimensions and layout are 95% compatible between OSI and Apple I/II keyboards, so the same layout will work for OSI, Apple II, and generic ASCII (inspired by ADM-3A).

I would appreciate any feedback. I'll probably throw in an AVR or PIC and create a stabilizer PCB before sending it off in the next few days.
unikbd.png (627.6 KiB) Viewed 3494 times


Re: Universal Vintage keyboard

Posted: Wed Jun 26, 2019 6:51 pm
by waltermixxx
I like the idea, it's awesome. Definitely a bring your own MX switches scenario. :)
OSI keycaps would be cool for it. Speaking of which I might need another set of OSI keycaps
for my next OSI caper, a C4P remake, i have the 542c keyboard board, and I have MX swiches
... :)

I would suggest holes for the space bar supports. :)
if this is straight up ascii keyboard, I'm in for one bareboard.

Cheers. :)

Re: Universal Vintage keyboard

Posted: Wed Jun 26, 2019 7:38 pm
by gekaufman
Very nice, and helpful as parallel ascii keyboards aren't easy to turn up.

I might suggest an Apple I compatible connector. Many folks are building Apple I clones and a nice keyboard option would be appreciated.

Now we need a case design. Perhaps a matching faceplate thru Front Panel Express?

Re: Universal Vintage keyboard

Posted: Sat Jun 29, 2019 1:17 pm
by glitch
I've been busy with a ton of work stuff, but I've pinged Dave about a possible case solution. Should be a lot cheaper than Front Panel Express (but then again, so is pretty much anything :p ).

Dave, how about some mounting holes around the interface connector so that an AVR, PIC, whatever interface board can be directly bolted to the back of the keyboard?

Re: Universal Vintage keyboard

Posted: Sat Jun 29, 2019 4:09 pm
by dave
Certainly. Perhaps even an arduino shield-compatible I/O breakout. All that blank space is intended to get a microcontroller, plus an expansion connector. I didn't want to put all the OSI sound stuff in there, but it would be reasonable to make an expansion board with a pin-compatible connector to add sound to this and vanilla 542 keyboards.

Re: Universal Vintage keyboard

Posted: Sat Jun 29, 2019 4:12 pm
by dave
For the microcontroller, one option is to write new firmware for a PIC or AVR, or ARM. I am most used to the PIC tools and peripherals, but prefer ARM for new projects, but AVR/arduino is probably what most hobbyists are comfortable with.

There's also the QMK project which might be overkill, but which appears mature and would be an easy way to get up and running with multiple keyboard layouts, and could be adapted for ASCII parallel output.

Re: Universal Vintage keyboard

Posted: Sun Jun 30, 2019 3:41 am
by Steve Gray
I'd actually go for separate pcb's. Make the keyboard matrix one pcb with a 16-pin connector (or more if you include the break key or others) and then an interface board. That way the keyboard pcb is smaller (no empty area) and the case could be smaller. The keyboard could be used on projects where the controller is not needed and different controllers could be designed for specific purposes and they'd be small boards too.


Re: Universal Vintage keyboard

Posted: Sun Jun 30, 2019 5:23 pm
by dave
That's a good idea. Breaking out all the electronics into a separate PCB could shave an inch or two off the height of the keyboard. Then, the daughter board could have anything on it. OSI multiplexed interface, an ASCII interface, etc.

I would probably break out certain keys as separate lines, such as potential shift-lock and break positions, which the daughter board could wire right in to the matrix, or intercept to produce RESET and soft shift-lock toggle.

Re: Universal Vintage keyboard

Posted: Sun Jun 30, 2019 8:13 pm
by glitch
Sounds like the most universal way forward to me!

Re: Universal Vintage keyboard

Posted: Sat Jul 13, 2019 5:29 am
by CommodoreZ
I'm vert interested in seeing where this goes. I can think of one or two uses for such a keyboard in my projects, where PS/2 is overkill.