LK201 emulation

[Ethan Dicks]

On Mon, May 18, 2020 at 6:47 PM sales--- via cctalk
<cctalk at classiccmp.org> wrote:
> On 2020-05-18 17:34, Steve Malikoff via cctalk wrote:
> > There is a project that seems to be going along the same idea,
> > http://www.kbdbabel.org/
> >
> > Steve.
>
> Except that I can tell you from experience that not all 4p4c terminal
> keyboards are interchangeable. I you plug a Wyse into a Televideo, or
> vice versa, the keyboard will not work, and sometimes causes a small
> fire....

That is very true.  DEC LK201/LK401, etc, and compatibles are all +12V
devices with +12V and gnd on specific pins (not mirrored or
mirror-safe).  I have, as I mentioned, a Planar terminal, an ELT-320.
It is a third-party device with an LK201 socket (and a PC-AT keyboard
socket - either one can be used).  Other vendors are free to do as
they please because they expect to sell you a device with their
keyboard.  I'm sure some are +5V devices and many are +12V.  Doesn't
take much of a difference to cause problems, especially if your +12V
line isn't current-limited.

Making a universal keyboard interface definitely faces some physical challenges.

-ethan