What was PL/M like, and should it come back? I've never used it.
As it looks like I'm the only one here who has used PL/M (for about 3 years) I'd put is somewhere between C and assembler. I still have a bit of a soft spot for it and would happily use it if a compiler were available.
I read above that PL/M is a stripped back PL/I. Having never looked at any PL/I source code until today I can see a vague passing resemblance but that might be the all-caps text fooling me.
I never used PL/M myself but have been looking at it closely recently, it was - at least initially - closely allied with the 8080, the language itself had facilities for interacting with DMA devices too it seems, may I ask, what kind of work did you do with PL/M?
PL/I was a designed, specified programming language. It was created after a detailed analysis of assembler, Cobol, Algol and Fortran. It had rich bit and packing/alignment features due to the cost of memory. Many programmers back then (1960s) had solid assembler experience and were no strangers to packing data into fields to conserve memory, so it was high on the list of the designers to give the PL/I programmer a similar ability to work at that level, this are received a lot of attention - all these years later that same mindset could apply to resource constrained MCUs.
It was a huge success and saw huge uptake in UK and Europe as well as Eastern block countries, it was marketed there differently to the US, where the costs of the language were rather high and this perhaps the biggest reason it became less well known over here. My first real programming job was a trainee programmer on PL/I on IBM mainframes in Enfield, London. Later I was hired to work in the City of London because Stratus hardware fault tolerant computer had started to see like hot cakes in mission critical environments (stock exchanges, investment banks, market makers). Stratus was interesting and had an OS written in PL/I subset G and was the preferred language to use on these machines, PL/I programmers were thus in demand and I got a job on that basis. The CTO of Stratus was interesting too, had a business developing and selling compilers (including PL/I) for Burroughs, DEC, Data General, Prime etc.
For those interested in computer history
here's an interview with him.
I've been particularly concerned recently with the grammar for a new language, once a grammar is defined there's no going back, one must live with the consequences of the choice for the lifetime of the language, PL/I's grammar is not perfect but it is perhaps one of the best imperative language grammars around IMHO.
I also developed a Subset G PL/I compiler during the 90s so I have solid experience of this, that compiler was never strictly completed but did generate linkable runnable COFF object modules for Windows NT, I wrote the entire compiler (except the small bootstrap start code which was assembler) in C, initially Borland then later Visual C, writing a compiler for PL/I in C was a unique learning experience, I saw the good. the bad and the ugly of both languages, up close, this was all before the internet too, so all research and design was driven by books and histiorical reprints of articles and papers from my local library.