Re: Offload from the AS/400 -Reply

> "Art Tostaine, Jr" atostain@crecomp.com> 
<snip> 

> BTW, my 10 year old Sys/38 program that
> was 16? bits, became 32 on the 400, and
> is now RISC-64, what are the advantages
> really to more bits, except that it runs
> faster, and isn't that mostly because the
> processors are faster?

> How can a CEO understand the benefits of
> 64 bit?

<snip>

           ------------

The advantage is essentially a wider data
path - tell the CEO it's like having a
bigger hose to fill his swimming pool.  You
can push much more water through a 4 inch
fire hose than you can through a drinking
straw, no matter how much pressure you
apply.  So, data flies around inside a 64
bit computer through a fire hose instead of
dribbling through a 16 bit drinking straw.

There's also the CISC-RISC factor, which
isn't related to # of bits, but it is
germane to "what's so cool about the
RISC-64 AS/400" discussion.  Tell your CEO
that a computer in reality sooo DUMB that
each time you tell it to do something it
has to "look up a recipe in a cookbook" to
find out just how it's supposed to do what
you asked it to do (it's called decoding,
but he doesn't have to know that).  RISC
processors only have a 2 page cookbook,
while CISC processors have a 1254 page
monster (intentional hyperbole to
illustrate the point), so they spend less
time paging through the book figuring out
how to do what they have to do and more
time actually doing it.

As far as your 10 year old program goes,
bear in mind that your source code may be
10 years old, but the underlying machine
code changed radically when you went to
RISC - ya remember that "Converting to 64
bit RISC" message you saw the first time
you ran your pgm?  In essence, OS/400
recompiled the code for you then (and
probably did some optimizing to boot), thus
creating a new object.  Sure, there's
probably a lot of performance bells &
whistles you could add now at the source
code level (user space as opposed to a work
file for temporary storage, for example),
but one of the really nice things about the
AS/400 is it tries to do some of that sort
of thing for you, so legacy code retains a
lot more of its value than it would on
other systems (oooh, a dollars & cents
argument - the CEO'll love that!)

Scott Cornell
Mercy Information Systems

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