Re: Microsoft OS/2 -- Ideal for Ada

[martillo@bloom-beacon.UUCP]

In classic unix, like I first used in 1975 the fundamental operating
system entities were files and processes.  If you understood
everything there was to understand about files and processes you
understood everything.  The tty was a file, the directory was a file,
and the pipe was an unnamed file.  The process was just about the only
entity that was not a file.  (Actually this is not quite true, there
were a few other objects like interrupt handlers which fit in neither
category) but in general there was nothing more which you really
needed to understand.

Multics was in some sense even simpler.  There is one fundamental
entity, the memory segment (though one could argue that the user's tty
was also a fundamental entity, but the importance of the user's tty is
perhaps more properly viewed as a result of the way Multics does I/O).
Unfortunately this seems to be a bad choice of fundamental entities
especially for me since I consider segmenting memory a stupid thing to
do  and based on a fundamental misconception that one wants to protect
regions of memory rather than operating system objects.

As for VMS and the various IBM operating systems, I am not sure what
the fundamental entities are and have the feeling that everything is
special cased which makes comprehension harder.