RE: Entry Parameters

["Shaw, David" <dshaw@xxxxxxxxxxx>]

-----Original Message-----
From: Alan Campin [mailto:Alan.Campin@CaseLogic.com]

Not to argue here. Maybe Hans could give use the true run down but all my
understanding in 20 years of technical journals and performance tips says
that the AS/400 is a packed decimal machine, the only one in the world. I
believe that this has been extended to allow efficient other types (Like
integer) but the native format of an AS/400 is packed decimal to the point
where the math is done in a base 10 format(for absolute precision), not base
2(Binary). In other words, the AS/400 is business data processing machine,
not a scientific machine. If you have ever had to work on a machine that
uses floating point number to represent decimal values and all the problems
inherent in that, you know what I mean. We are really spoiled on the AS/400
because we never have these kind of problems. 

Everything I have read says the AS/400 takes a zoned value, converts it to
packed decimal, does the arithmetic in Base 10 and then converts the result
back to zoned. 

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

My understanding is that the AS/400 directly supports packed decimal, zoned
decimal, integer, and floating point arithmetic.  Many of the major business
computers support decimal arithmetic without resorting to floating point - you
don't think that S/360, S/370, and S/390 machines only do floating point and
integer, do you?  Or that business machines from Burroughs or Sperry Univac had
that kind of disadvantage relative to IBM?  After all, the COBOL standards
specify support for decimal arithmetic in COBOL programs.  My experience is that
the decimal arithmetic issue mainly applies to the scientific machines, things
like VAXes and Unix boxes.

As for the implicit conversion to packed, I have read a number of times that
it's the RPG III compiler that does that, not OS/400 and not the hardware.

Dave Shaw
+---
| This is the RPG/400 Mailing List!
| To submit a new message, send your mail to RPG400-L@midrange.com.
| To subscribe to this list send email to RPG400-L-SUB@midrange.com.
| To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---