As it turns out this project was quite trivial to put together. Maiko has done all the hard work with his software and John Hanson, W2FS did more hard work with his TNC-Pi hardware
The top 2 pictures show a RPi3 and a TNC-Pi housed in the PiGate 3D printed enclosure (should have printed it in OEM Orange!). The bottom picture shows the completed PiGate hardware connected to a KPC3+ via a direct audio cross-over cable.
So how do I build the JNOS? I started with a shiny new 8GB SD card that I picked up at Microcenter for $4 and a RPi3 which I also got from Microcenter for $30. I also downloaded the latest edition of Raspbian Jessie Lite. The Lite version does not have a GUI. Real men can use the Linux command line. /JFDI!! I'm not going to tell you how to install the RPi and get it onto your network. There are plenty of other resources available for that.
Before we start, have you confirmed that your TNC-Pi works correctly? You can use the tools from the TNC-Pi website to talk to the modem? You removed and added lines per the instruction on the website? Good.
Let us start by installing the the latest updates, patches and a few required libraries ...
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install libssl-dev libncurses5-dev libncursesw5-dev
Now get the latest sources from Maiko's website and unpack it. Navigate to the 'src' directory. Copy the config.h.default file to config.h and edit it to your requirements.
Now for the hard part. Go ahead and 'make' JNOS. It'll take about 10 minutes so go and make a nice Brownian Motion producer.
So it's JNOS, right? So that means you'll need to craft all the relevant config and support files, autoexec.nos, ftpusers, rewrite, forward.bbs etc. But just to be nice I'll give you a head start on the modem config in autoexec.nos ...
#And that's really all there is to it. As stated previously I connected the RPi/TNC-Pi directly to my KPC3+ via a cross-over cable. I was able to connect to the JNOS BBS prompt as seen below. It just works.
# ---------- TNC-Pi specific----------
# We are using a single TNC-Pi KISS modem from Coastal Chipworks (hi John!!) configured to use the serial port @ 19200bps
attach asy ttyAMA0 - ax25 pitnc 1024 256 19200
# That's all. Carry on with the config
Some links ...