Thank you so much for getting back to me. Your thoughts on this make me realize that I could be worrying needlessly. I really appreciate your help.
I currently use different but quite ordinary USB keyboards for my work, depending on my location. The brands are different. One is a “Microsoft Wired Keyboard 600”. I think another is a Hewlett Packard or Dell branded keyboard. These are all wired as USB-A connections. All have a number keypad at far right., arrow keys/prt sc/home/insert/del/pgup/pgdn to the left of the number keypad, and a QWERTY keyboard (in English characters) at far left. Above the QWERTY keys is a row of function keys, F1 through F12.
I don’t know the data flow for certain, but I believe that when I use InfoConnect Workspace terminal emulation software, it accepts the USB scancodes that my typing produces, and translates them into e.g. EBCDIC character codes. On IBM mainframes, one uses the EBCDIC character coding, and I am guessing (without knowing this for a fact) that in the 1970s, one had to purchase or lease 3270-type terminals and keyboards, and these 3270 keyboards only understood EBCDIC encoding. There was no such thing as Universal Serial Bus in those days. Everything was proprietary and hardwired.
My original post above talks about “3270-compatible keyboard codes”. I made a mistake in saying that. The reference to “3270” is more about a hardware type, end user terminal specification that comprised both a keyboard and a display device, rather than a character encoding. I should have been talking about mapping USB scancodes to the corresponding EBCDIC character codes that an IBM z-Series mainframe understands. Thank you for clarifying that for me.
Based on your explanation – I should be able to use the UHK on a mainframe, although with a very limited set of Program Function (PF) keys. Yes, those do map to Function Keys F1-F12 on a standard USB keyboard. I use F3, F7, and F8 the most; these map to PF3, PF7, and PF8. I can probably buy a UHK key cluster and map those 3 keys to PF3/PF7/PF8.
I think I may need to edit an InfoConnect Workspace keyboard map so that it fits the UHK as best as possible. I will talk to some contractors at my office to see what they think is possible with a custom keyboard mapping.
Thanks again for responding to me. I will give this more thought, and decide what to do.