Joe
How much memory would a machine running PC-Dos (or MS-DOS) these days need
to run efficiently (not a lot in my reckoning?), and what would the
performance be like, would this be similar to an IBM i?
OS/400 is good because nobody can mess with it (and why should they?) But
that doesn't imply superiority over others where they can. So what do you
do, stick with something that works, or invent something new?
(It is reckoned by some that Leo Fender got it right first time with the
Fender Stratocaster, so why change anything ever?)
- Maurice (Not that I'm known for changing the subject line or anything)
A von Neumann machine is one where the program code is modifiable. The
program code for the i is essentially not modifiable, hence non-von
Neumann. The primary upside is that program code can be shared among
multiple jobs, since it can't be modified.
There's no opinion there, so I don't get your "must think of something
else" remark. Are you inferring that I consider the midrange better
than other operating systems because they are non-won Nuemann? I do
think the midrange is better than any other operating system, but the
non von-Neumann nature is only one part of that. And to be pedantic
about it, it's not really "non von-Neumann" since the program code can
be updated, but only by the operating system not by application
programs. So calling it non-von Neumann is more of a convenience term.
And just to expand on that, whether or not read-only code is "common" is
not really the point. The point I was making is that the IBM midrange
is built around this concept and takes advantage of it in many ways.
That's why entire enterprises with hundreds of users could be (and in
some cases still can be!) run on machines whose total memory is measured
in megabytes, while a typical Windows user needs 4GB just for their
desktop machine.
So, yes, other operating systems have shared code. But like so many
things, the i has had it for a much longer time. The IBM i - we have
technology before technology is cool <smile>.
Joe
Den 31/12/10 22.23, Joe Pluta skrev:
Yes it does. It's called a job. That is the state management on the
i. It's built for that, because all the jobs share the same program
space. The i is a non-von Neumann design in that jobs share an
essentially non-modifiable program space. Thus when you run hundred of
Out of curiosity, why is the above a non-von Neumann design?
Memory mapping shared read-only code is not uncommon these days, so you
must think of something else.
midrange.com
