In 1985, I took an evening class in APL at the local IBM as part of a high school Explorer Post (which was really cool, these guys giving up their time to teach us programming). Other than this, I am woefully inexperienced in computing on IBM machines.

Now, this was 1985, so the monitors and keyboards were already set up for us to just work without overstriking. HOWEVER, I proved to have some small talent at APL programming, so the guy took me aside and said he wanted to get me going on APL2, and gave me a complete set of manuals. ("We only have two copies of these. One we're keeping, and one is now yours." Like I said, really cool guys.)

The keyboards were NOT set up for the new APL2 functions and operators and so a form of "overstriking" was needed by typing two symbols with an underscore in between. On the older monitors, that's how it was rendered, as three characters and you just had to remember that this represented a single symbol.

But they had a handful of newer monitors that when any of these APL2 specific characters were entered with "overstriking", the symbols would sort of gloomph together and be rendered as a single-character APL2 function or operator despite there not being a key for it on the keyboard.

Does anyone know what that monitor might have been? I assume this was handled as a form of hi-res graphics, since I doubt these symbols were in the monitor's character set. A pittance of Google research has said that the 3179G was available around that time, and it had hi-res graphics. But I honestly have no memory of the model I used to program APL2 in those days.

  • 6
    My guess would be some variety of IBM 3270 terminal. These had an APL character set built in, so even it if was a "...G" 3270 with graphics, that would be irrelevant. All the 3270 versions look quite similar.
    – alephzero
    Commented Apr 17, 2020 at 16:09
  • No, actually, it is quite relevant. I agree that it was some variant of the 3270, While they all had the APL character set built-in, they did NOT have all have the ability to render the APL2 character set; I'm specifically seeking suggestions for monitors that had that ability, which is why I'm postulating the 3179G.
    – TZFan
    Commented Apr 17, 2020 at 16:54
  • 1
    @TZFan: Are you also the author of this question? Two different accounts, but both named "TZFan". Also, both questions are titled "What ___ am I thinking of?" It sounds like you are asking us to read your mind, which is not what StackExchange is about. The questions can and should be re-worded.
    – DrSheldon
    Commented Apr 18, 2020 at 4:01
  • Please forgive me on both counts. I did write the other question; I know nothing of two accounts; comments relevant to each question are entering my inbox. However, if I have two accounts with the same name, that would explain why I've needed admins to approve edits to my own question. Why on earth would two identical usernames even be allowed?
    – TZFan
    Commented Apr 18, 2020 at 11:41
  • 1
    Combine two accounts
    – dave
    Commented Apr 18, 2020 at 12:17

4 Answers 4


Some 3270 terminals supported an optional Programmed Symbols feature, allowing the use of arbitrary character bitmaps. This was available on the 3279 Color Display Station (models 2B and 3B), the 3278 Display Station (models 2, 3 and 4) and the 3270 PC (with the Programmed Symbols card).

  • This is very interesting; thank you for sharing this with me. Perhaps it was some version of the 3279 or the 3278. It was so long ago, and I used it so briefly, I will probably never remember, but I shall look into these. Thank you!
    – TZFan
    Commented Aug 2, 2020 at 23:14

I realize that it's been over a year, but thanks to all for responding. The terminal in question WAS a 3179G. I had figured it must have been because it had the graphics ability to render the APL2 characters (the standard APL characters were part of text mode on most of the terminals at that time).

However, it turns out the 3179G did have the APL2 characters preprogrammed as part of text mode. It was the first monitor to have this. The complex procedure I had to use to enter these characters was not due to their being weird graphics renderings...but simply because these characters did not yet appear on the keyboard!


1985, it could have easily been any IBM PC equipped with a Hercules Monochrome Graphics card. More likely, however (as you said this was on IBM premises), the machines capable of displaying the full APL character set were XT-370, mixed-mode beasts consisting of a PC/XT, a terminal emulator and dual-Motorola 68000 for the emulation.

  • Maybe, then again, this sounds wy more like a classic 3270 setup - which had versions to do APL, in various level, decades before any PC.
    – Raffzahn
    Commented Jul 27, 2020 at 22:00
  • Yeah, I doubt it would have been the XT-370. I think far more likely would be some sort of IBM terminal - or IBM PC AT as terminal - connected to an IBM mainframe. If it was an IBM AT, it would not have been with a Hercules as that was not an IBM product. IBM didn't invent everything themselves (printers made by Epson, etc.) but while the Hercules card was a fantastic product, I don't think you'd see it at IBM. You might see (as I did, same time period, at U of MD) some advanced IBM displays, or you'd see standard commercial IBM stuff (in this case, MDA, CGA, EGA). Commented Jul 28, 2020 at 2:33
  • @manassehkatz-Moving2Codidact I think that what I was saying?
    – tofro
    Commented Jul 28, 2020 at 13:54
  • @tofro Sort of. I'm saying that Hercules, in this IBM context, would be very unlikely, not just "less likely", and that XT-370 (while a fascinating machine - I remember reading about it at the time) was much less likely compared to "PC or terminal connected to real mainframe." Commented Jul 28, 2020 at 14:17
  • 1
    I'm the OP. It was a mainframe of some sort, not a PC. This was on IBM premises and we borrowed offices to work on our projects. And, to be clear, I'm not inquiring about APL, which ALL the terminals could render, but APL2, which at the time was a brand new language, and only a handful of terminals could render it at the plant we were at. My speculation is that it was a 3179G, which COULD render the characters, and was a new model, so that there would be a few available onsite, but not too many.
    – TZFan
    Commented Aug 2, 2020 at 15:03

The 3270 would have needed to be connected to a mainframe, you didn't mehntion the setup.

If you remember the system as being standalone, it could have been a 5120 https://en.wikipedia.org/wiki/IBM_5120 that supported Basic and APL - selectable by an actual switch as in hardware :-)

  • Say, how do you know which system the OP used? Also, APL was available on many machines in the IBM environment with mainframes being a major usage.
    – Raffzahn
    Commented Aug 1, 2020 at 15:45
  • I'm the OP, and I do not remember which system was used. It was a mainframe. However, to be clear, my question is not about the APL character set (which ALL the terminals there could render); it's about the APL2 character set, which could only be rendered by a small number of terminals onsite and so I had to be selective about which one I used. My "deductive speculation" is that it may have been the 3179G, which could render characters beyond the normal EBCDIC or APL character sets and which would be new enough that there would be a few of these terminals, but not a whole lot of them.
    – TZFan
    Commented Aug 2, 2020 at 15:00

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .