[Info-vax] [OT] Wirth style languages, was: Re: Obscure Ada compiler vendors?

[David Froble]

Phillip Helbig---undress to reply wrote:
> In article <kjkvcs$16l$1 at dont-email.me>, David Froble
> <davef at tsoft-inc.com> writes: 
> 
>> I'm guessing one of the major goals of Java was to run on just about any 
>> hardware and OS.  It's not real efficient, but, for most uses, it 
>> doesn't need to be.  When you're doing something only once, you don't 
>> need efficiency, you need ease of use and universal use.
>>
>> Fortran, Cobol, and other compiled languages are meant to be good at 
>> doing things many times.
> 
> OK.  But the discussion started around languages to write an OS on.
> Surely there one is talking of compiled code and not the
> one-size-fits-all Java approach.
> 

I'm definitely NOT the best person to answer this, as I've never written 
an OS.  I'm sure there are people who know the various pieces of an OS 
without really having to think about it.

What is an OS?  Well, as much as I know, there are some rather low level 
stuff, tables, schedulers, and such that cause things to happen.

Then there are services for applications to use, things like the system 
service calls on VMS.

In addition, so that users can actually do something, there are the 
utilities.  These are actually applications, and have little to do with 
the actual OS.  These would be things like SEARCH, TYPE, FTP, and such. 
  As applications, they could be implemented in just about any supported 
language.

But what is sometimes called the kernel has no outside support. 
Everything needed must be present.  No Java virtual environment and 
such.  Or as recently discussed, no ADA run time library outside the 
image to support the image.  For this, you need tools that can produce 
an image that once loaded and started contains everything required for 
it to run.