LK201 emulation

On Mon, May 18, 2020 at 5:20 PM Electronics Plus via cctalk <cctalk at classiccmp.org> wrote: LK201 keyboards and variants (LK401, clones, etc) have a narrow 4p4c "handset jack" connector, not offset like an MMJ serial connector. The power is +12V, the serial protocols are the same. I've used LK401s on VT220s and Rainbows, I've used LK401s and LK201s on a Planar terminal with an "LK201" input jack. That part is standard. Speaking for myself, I have a pile of devices (DECmates, Professionals, Rainbows, VT220, VT240...) that have a 4-place narrow handset jack for a keyboard, and most of them are expecting an LK201. I also have a large assortment of LK201s (with and without the WPS/EDT "Gold Key" keycaps) and 1-2 smaller but compatible keyboards. Every time I pull an LK201 off the shelf, I'm wondering if it's going to work. I have 2-3 dead ones for sure. I think at least one of them has a dead matrix because IIRC, it was causing "4 - keyboard error" until I dismantled it and unplugged the mylar keyboard matrix sheet. I suspect that the paint layer has either oxidized to high resistance/open circuit or there's a short somewhere. I haven't investigated that further. I am also aware of some electronics failures. I can obviously mix and match bits to have as many working keyboards as possible, but that is a finite decreasing number. What I would find handy in one regard is being able to use a PS/2 or USB modern keyboard on 1980s DEC equipment as if I was plugging in an LK201. I would also probably employ a device that I could plug a real DEC keyboard into but that talked PS/2 or USB to be able to use that with a modern machine. One application would be to use it with Simh or even just a dumb terminal emulator (Glass, etc) with a real terminal feel. I might employ a device that replaced the electronics in a dead LK201 but I wouldn't need that many of them. -ethan