There is MULTICS, which was released as open source a while ago, and an emulator was written for it also.
Since MULTICS had a high quality PL/I compiler, you can install the emulator to play with the language. The "shell" is different from Unix but shares some similarities.
Interesting that it is available for OS/2 and not Windows.
If you are already supporting Linux and OS/2, it isn't much more work to support Windows too–and will likely attract many more users than OS/2 support will
The FAQ [0] says:
> Iron Spring PL/I is free for non-commercial and hobbyiest use. The price of the commercial version has not yet been determined, but will be approximately two orders of magnitude less than IBM's compiler for Windows. Academic, Government, and Volume licenses will be available. A CD will be available at additional cost.
I'm sceptical the commercial version is ever going to happen now. This is a very small and shrinking market, 20 years ago selling it would have been a tough gig but you might have had some success, the same success today is going to be orders of magnitude harder. If you had a time machine to take this product back to the 1990s, it probably would have done much better, though even there it would have been a decisively niche product.
> The compiler is currently closed-source.
I wonder why people do this – I get why you want to keep your software closed source if you have realistic plans to commercially exploit it – but if you don't, why not just let people have the source code?
I've heard before stories about solo closed source developers who suddenly and unexpectedly die, and they'd left the source code on an encrypted disk, and even if their family gives some technical friend permission to try to retrieve it, turns out to be impossible because nobody knows the password. Open source, not an issue.
> I've heard before stories about solo closed source developers who suddenly and unexpectedly die, and they'd left the source code on an encrypted disk, and even if their family gives some technical friend permission to try to retrieve it, turns out to be impossible because nobody knows the password. Open source, not an issue.
I feel we need more code escrows for that reason. Keep it commercial till you die, fine, but let it live on afterwards.
glhaynes · 4h ago
Best guess: that's because no organizations are writing their first PL/I apps in 2025; and there aren't many PL/I-using organizations who weren't big IBM customers, who largely migrated from OS/2 to Linux. So I wouldn't be shocked if a Windows version wouldn't bring in enough money to make even a relatively easy port worth it.
Next-to-best guess: author was an OS/2-head, many of whom have been hating M$ Windoze for 30 years at this point! Ah, those were good days.
skissane · 3h ago
> So I wouldn't be shocked if a Windows version wouldn't bring in enough money to make even a relatively easy port worth it.
True, but I’m sceptical the Linux or OS/2 versions have ever brought in any money either.
This looks to me suspiciously like a hobby project masquerading as a commercial venture
pdw · 5h ago
According to their news page, they started development on OS/2... in 2007... Amazing.
> 5 Nov, 2007: Iron Spring Software announces the availability of the first alpha version of their new PL/I compiler. The alpha runs on the OS/2 operating system only.
kjellsbells · 1h ago
I dont sense much love in the comments, but I find this kind of computing niche kind of useful. There is more to life than arguments over Rust. Computer systems can have lifetimes measured in multiple generations. Etc. It is interesting to see what is going on elsewhere in the galaxy, so to speak.
These guys seem passionate about what they do in the same way that other niche companies are, e.g. Isode with X.400 or Arca Noae on OS/2. Good luck to them.
The blurb for their lead guy claims he's been involved in PL/I since 1965. I'm estimating that would make him 80 now. If he is still cranking out compiler code at 80 I hope this is a golden years/fun project for him.
Koshkin · 5h ago
./plic advent.pli
(ERR999)No valid statements in source program
(Goes back to reading an article about Common Lisp.)
This was my first programming language. CS 101 was taught in PL/I, on punch cards, when I went to college. We actually used a Cornell dialect called "PL/C"
While it's called "Pee el one" it's rendered PL/I. So the title is wrong; the article has it correct. Please fix it! See: https://en.wikipedia.org/wiki/PL/I
SoftTalker · 33m ago
Same, first CS class used PL/I though we used terminals not punch cards.
Polizeiposaune · 2h ago
In the context of Multics it was generally spelled "PL/1" rather than "PL/I" (the latter being IBM usage); source files named xxx.pl1, compiled with the "pl1" command. See for instance https://www.multicians.org/pl1-raf.html
Since MULTICS had a high quality PL/I compiler, you can install the emulator to play with the language. The "shell" is different from Unix but shares some similarities.
About 3/4 of the way down this page, is the PL/I source code: https://multicians.org/pl1.html
If you are already supporting Linux and OS/2, it isn't much more work to support Windows too–and will likely attract many more users than OS/2 support will
The FAQ [0] says:
> Iron Spring PL/I is free for non-commercial and hobbyiest use. The price of the commercial version has not yet been determined, but will be approximately two orders of magnitude less than IBM's compiler for Windows. Academic, Government, and Volume licenses will be available. A CD will be available at additional cost.
I'm sceptical the commercial version is ever going to happen now. This is a very small and shrinking market, 20 years ago selling it would have been a tough gig but you might have had some success, the same success today is going to be orders of magnitude harder. If you had a time machine to take this product back to the 1990s, it probably would have done much better, though even there it would have been a decisively niche product.
> The compiler is currently closed-source.
I wonder why people do this – I get why you want to keep your software closed source if you have realistic plans to commercially exploit it – but if you don't, why not just let people have the source code?
I've heard before stories about solo closed source developers who suddenly and unexpectedly die, and they'd left the source code on an encrypted disk, and even if their family gives some technical friend permission to try to retrieve it, turns out to be impossible because nobody knows the password. Open source, not an issue.
[0] http://www.iron-spring.com/faq.html
I feel we need more code escrows for that reason. Keep it commercial till you die, fine, but let it live on afterwards.
Next-to-best guess: author was an OS/2-head, many of whom have been hating M$ Windoze for 30 years at this point! Ah, those were good days.
True, but I’m sceptical the Linux or OS/2 versions have ever brought in any money either.
This looks to me suspiciously like a hobby project masquerading as a commercial venture
> 5 Nov, 2007: Iron Spring Software announces the availability of the first alpha version of their new PL/I compiler. The alpha runs on the OS/2 operating system only.
These guys seem passionate about what they do in the same way that other niche companies are, e.g. Isode with X.400 or Arca Noae on OS/2. Good luck to them.
The blurb for their lead guy claims he's been involved in PL/I since 1965. I'm estimating that would make him 80 now. If he is still cranking out compiler code at 80 I hope this is a golden years/fun project for him.
While it's called "Pee el one" it's rendered PL/I. So the title is wrong; the article has it correct. Please fix it! See: https://en.wikipedia.org/wiki/PL/I
Fixed.