IBM Mainframe terminal stuff

Guy Sotomayor ggs at
Fri Dec 18 17:00:15 CST 2015

I’ve been tinkering around with my IBM Mainframe terminals and I’m pretty close to having everything the way that I want it.

I currently have an IBM 3174-61R Establishment controller connecting to my “mainframes” via TCP/IP.  This allows me to not only connect to my Multiprise 3000 S/390 but also some PCs running Hercules to allow me to run older versions of the mainframe OS’s.  I currently have 3 IBM 3179 terminals hooked up.

I’ve upgraded the 3174 to be able to boot from a hard disk (it was a supported option).  I actually purchased the upgrade from a reputable vendor but after many attempts we could not actually get it to do anything useful.  I learned about DavidG’s MFM emulator and that’s now installed in the 3174 which happily boots from it.  I still have to figure out a permanent mount for it since the standard 3174 HDD mounts don’t work for the MFM emulator board.

One of the last things that I wanted to figure out was how to support multiple sessions.  I had configured the 3174 to support multiple sessions on each terminal but following the documentation, I could never figure out how to actually switch between the sessions.  Well today I managed to do that.  Success!  I finally figured out the key sequence for switching sessions.  It doesn’t match the IBM documentation.  It’s not clear to me if that’s because I haven’t configured something properly on the 3174 or if there’s some other reason behind it.

Since I also have the AEA feature that allows me to connect ASCII terminals to the 3174, my next project will be to hook up a couple of the terminals that’re deemed “compatible” (VT100, ADM5 are on the list) and see how that works.  But that also involves navigating the 3174 configuration process which is opaque to say the least (there are configuration screens but you need a manual because the fields only have numbers (e.g. 721) to identify them and no other indication as to how they need to be filled in).

Oh, the other bizarre thing about the 3174 that’s been configured with TCP/IP is that I can also connect to “unix” servers with the 3174’s (and the ASCII terminals too).  It’ll be interesting to see how that works on a CUT mode terminal.  ;-)

TTFN - Guy

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