IBM 3270 compatible terminal connected to Hercules IBM mainframe emulator.

Mattis Lind mattislind at
Tue Sep 1 06:51:04 CDT 2020

Hello Connor!

Den tis 1 sep. 2020 kl 01:58 skrev Connor Krukosky via cctalk <
cctalk at>:

> Wow Mattis this looks great, fantastic work!


> I will see if I can solder up a unit from what you have up on github on
> a perf board (I should have a few bluepills kicking around) and see if I
> can assist in some way with testing on a 3174-61R I have.

That should be easy to do on a perf board. And if you don't have MAX208
around you can replace them with something similar. Maybe the 3174 is not
so picky about interface signals and only need CTS so you could probably
skip most of them? The 9 pin serial port is not really necessary and is
mostly used for debugging. Two senders or three if CTS is required and one
receiver should be enough.

> Unfortunately its the only one I have and I have a few 3270 terminals so
> I would like to keep it in my ownership.

Sure. But if someone hears about a spare 3174, preferably the smaller ones,
I would be very interested. I have a 3279 and a 3178 that could be
interesting to test. In the longer run it would be interesting to do SDLC
integration over VTAM as well. The SDLC implementation on the STM32 seems
to work quite well, but there is quite a lot of work needed on the
comm3705.c code inside Hercules to get all things together.

> But they definitely do show up, a lot more often than it seems the
> terminals do nowadays.
> I have the Ethernet controllers for my 3174-R61 which I know people
> generally use for communications with things like Hercules but as those
> are much less common it would be nice to see if we can verify this works
> on these terminal controllers and make using 3270 terminals with
> Hercules more accessible to people!

> If you'd like me to work with you on testing this let me know. I'll
> definitely see if I can try it out myself anyway.
> Either way, fantastic work and thanks for putting everything up on github!

I have one tester now that has ordered boards and built one to connect to a
3174 with 3179 and 3178 terminals so I guess that I will get reports from
him if it isn't working. It is always nice with more testers, but there is
no hurry. If you do build one I am happy to help you get it working.


> -Connor K

More information about the cctech mailing list