Michael S Hines wrote:

Likewise for the IBM Mainframe operating systems MVS,OS/390,z/OS - much of
which is written in (I believe) PL/M - a dialect much like PL/1.

If PL/M is the language I am remembering from an embedded systems class back in the 1980s, then it is not at all like PL/1. Rather, it is a completely type-unsafe language. I would say "similar to C", in that it has most of the same pitfalls. However, where ever C made an arbitrary decision (either way is just as good) PL/M went the opposite direction from C, making it very annoying for a C programmer to use.

Many of our Operating Systems seem to have evolved out of the old DEC RSTS
system. For example, CP/M had a PIP command. Later renamed to COPY in DOS.


When you've been around for a while, you start to see the same features
converge.. UNIX had quotas, we got Quotas with Win XP Server (well earlier,
when you include the third party ISVs - as an add on). IBM had Language
Environment (LE) before .NET come along.

I think .Net borrows most heavily from Java. Java in turn borrows from everyone. The "managed code" thing in particular leads back to the Pascal P-code interpreter; a kludge to make the Pascal compiler easier to implement and port. The innovation in Java was to take this ugly kludge and market it as a feature :)


Crispin Cowan, Ph.D.  http://immunix.com/~crispin/
CTO, Immunix          http://immunix.com

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