Nice project! I hope the schematics how to connect the to the ISP to program the terminal emulation and the pinout how to connect the Raspi/whatever to the onboard serial follows soon. ;)

The ISP pads are in a standard 6 pin layout:
https://upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Isp_headers.svg/1200px-Isp_headers.svg.png

As for the serial connection, CL_FLASH is your TX, and the right leg of the power switch on the smart response is your RX.

Thank you Odel. I've soldered the ISP connector. I used https://learn.sparkfun.com/tutorials/atmega128rfa1-dev-board-hookup-guide/arduino-compatibility as the "board" to compile it with the Arduino IDE, exported the compiled binary and programed with

avrdude -p atmega128rfa1 -c usbasp-clone -U flash:w:sketch_jul16a.ino.rf128.hex:i

The via left to "CS_Flash" outputs serial TX at 9600bps and the RX pin is the "lower" right leg of the power switch that accepts 9600bps serial input.

Is anyone that has gotten this working figured out how to get ubuntu to properly scale the terminal at boot time?  Using a Banana Pi M2 Zero with uBoot and my cursor ends up all over the place.

Odel, you need to connect serial to the Serial 1 header which is the CS_Flash VIA and the right foot of the on/off switch for rx and tx.. don't remember off the top of my head which is which right now..

That did the trick, thanks!

I've got the code flashed and working.  Eagerly awaiting schematics, can't seem to get serial data from a pi zero to display, even with what I believe are the correct pins bridged.

I hope you release your code for the VT100 emulator. I just picked one up off ebay and I'm looking to put a pi zero in it as well. Turning this into a simple text-only console to the Pi, with a USB port to connect things like serial adapters, would be super handy.

I'm planning to release the source code on the end of next week! :)

Keep updated on my GitHub account https://github.com/chmod775

Pretty interested in duplicating this at least partially. I actually have a Neo Air as well but i wonder about fitting more flat lithium batteries in it and using a say a banana pi m2 zero, which is the same formfactor as the rpi zero w. Though of course the zero w would probably have the best battery life.

The first funny thought i had was to turn it into a Rogueboy - a portable device for playing roguelike games. Unfortunately, i think most of them depend on an 80x25 character display so probably most if not all of them would require some coding to allow them to slide around in a smaller terminal. 

I guess the minimum application would be your vt100 emulator + an esp32 running an ssh client. 

My measurements suggest that it might be possible to fit two of these inside the XE, on either side of the battery compartment after removing the internal ribs: 

https://www.aliexpress.com/item/32834583326.html

and i found this boost converter + charge controller that maybe can be tied to the same power button as the main board: 

https://www.aliexpress.com/item/33006961652.html

I placed orders, so in 2-10 weeks we shall see.

This is a pretty cool project. I am always excited to see what people do with these things. Pretty cool devices and it looks like the perfect size for a handheld. I loved programming on my TI-84, and this seems like it would feel similar.

When will the VT100 Emu code, at least, be released (if you know)...?

Also, I'd love to see something that could operate as a serial X11 terminal from a RasPi Zero 1.3 or Zero W -- I realize that the screen size is extremely limited (not to mention just plain weird!) at 384*160, but the ST75686S LCD controller in there at least purportedly has support for a 4-shade grayscale mode; I'm not sure if that's enabled in the hardware tho (actually, it looks like that's a software enable/disable thing only). The X Window System, historically, was actually *designed* to work over a network -- hence the client/server architecture and nomenclature -- although I'm told that a lot of the functionality that was originally in place for that was eventually removed.

But if there's somehow a way to get a bare-bones X11 Server (yeah, the *Server* is the display! It's crazy...), with at least limited graphics capability, running on this kind of hardware, I'd love to see that.

X11 seems unlikely to me, due to the ram limitations, but a VNC viewer with x11vnc on the other end is probably very doable. 

Nano-X aka Microwindows i guess is an outside possibility since it has been ported to some pretty minimal systems. 

I'm planning to release the source code on the end of next week! :)

Unfortunately X11 seems unlikely to run on a simple ATmega128RFA.

The best plan would be to develop a custom PCB and a custom kernel driver to drive the ST75686S controlled LCD.

!!! How do you fit all that text on that screen?!

I mean, Nano-X / MicroWindows is listed as running on m68k architecture, which is 16bit... sort of (it's uhm complicated, it's a hybrid architecture)... and not much better at its bottom end (remember the 68008!) than that ATMega, if at all.

I think it's worth a shot... but I'm all hardware, no software. Do you have time to give it a shot?

Perhaps the AVR could be dedicated to just drawing on the screen, while an esp32 handles the network connection and the x11 protocol with a port of nano-x. Since x11 needs a socket anyway, and without some additional hardware somewhere you don't have ip access in this device anyway. 

But I'm just spitballing. Way beyond my ability. 

fwiw, someone has released an esp32 ssh client/server library. Could build a wifi dumb terminal maybe. 

This was recently tweeted about by microchip, in case you've missed it :)

https://twitter.com/MicrochipMakes/status/1418644626265845762

Thanks man! Totally missed it :)

Love your projects!

Also, It's featured on Hackaday.io.