> On Jan 7, 2026, at 12:47 PM, Richard via cctalk <[email protected]> wrote:
>
> ...
> If you're really paranoid about damaging either the keyboard or the
> terminal, you should use a voltmeter to identify which pins on the
> connector are power and ground and make sure that they both the keyboard
> you're going to try and the terminal agree on which pins are used for
> power and ground. The remaining pins are going to be the serial transmit
> and receive, likely at TTL levels not RS-232 levels.
I have no idea about non-DEC terminals, but the LK201 uses real RS232 levels.
Those are bipolar (plus or minus 5 volts or more) and if you connect that to a
device with a TTL input it may be unhappy. Typical TTL level logic devices
object to negative input voltages more than 1/2 volt or so.
You could look for the output pin on the keyboard connector of the terminal,
ideally with an oscilloscope at power up because it's likely to send some setup
sequence. If you see +/- 5 volt or so signaling, that would be RS232. If it
swings between 0 and 4-ish volts it's TTL and an LK201 would not work. You
could use an RS232 transceiver chip to convert the signal levels, that's easy.
Or take my LK201 emulator with the RS232 transceiver omitted and replaced by a
few jumper wires.
paul
