[GreenKeys] Feeding ITTY to the teletype; simulating M33/35 teletypes hooked to computers like in the 70s

[Paul Heller]

I'm experimenting with something, but it is very early days. There are small computers, the size of an Altoids (the mints) tin. These full fledges computers run linux.

I have ordred two different types. One is called a Raspberry Pi. You've seen Don post about this.  Since I don't have it yet, I can't say anything about it.

The other is more expensive and is called the Beaglebone. What I know about the Beaglebone is that you can add  card to it called a cape. It also has an ethernet port.  I ordered a blank cape which is basically a breadboard. 

My aim is to build a current loop circuit on that breadboard and write some software to grab the ITTY feed from the internet and process that feed into the mark and space for the current loop. Maybe this can be switchable for 20ma or 60ma. The software aspect has me a bit nervous. My C and C++ skills are rusty, my linux skills non-existnat, and I don't really know how to process audio. 

Couple that with my basic, rudimentary skills in electronics design and this could take a while.....   

I must be crazy to try this the experiments and frustrations might be fun.

My dream would be to have a device to give you folks so you could operate ITTY on your teletypes without needing your computer nearby. Not sure if anyone would be interested in it, but it is a dream.

On a related note, I am also aiming to set things up so I can run the simh simulator on the Beaglebone  (or Raspberry Pi) and transmit its output to M33 or M35 teletypes. In this configuration it will replicate the M33 running on old iron (simh seems to support many different computers including PDP-8 and HP/ACCESS and many others) in a device so small it fits in the pedestal of the teletype. This one actually might be easier because the device has a built in USB connector so it should be possible to route the RS-232 through the USB port which can then can be run through a USB-serial adapter and then a telebyte (or similar) RS-232 to Current Loop converter. Once that is working, the project to eliminate the USB-serial adapter and teleybyte converter (via the cape) could be tackled.

OK, these two projects are very ambitious for me (maybe too much so!) and many many people could do in a week what will most likely take me months to accomplish. But until someone else gets it all running before me I'm going to work on it at my  own pace.

Does anyone see why this idea would not work? Any comments or suggestions?

Paul
KD0DFR