[comp.sys.hp] Floating point accelerator 98248a

wittmann@engr.wisc.edu (art wittmann) (08/15/89)

I just got a 98248a FPA for my 9000/360.  Our EE department uses the
circuit simulation program 'spice' heavily, so I recompiled spice to 
take advantage of the new FPA (using the  +ffpa switch to cc).  I ran
a couple of test programs and saw about a 10% performance increase.  So,
two questions:      

1. Has anyone used the FPA for such "real world" applications & what 
   kind of performance increase have you seen?

2. Do I have to do anything else to get full use of the FPA (use other
   libraries when linking spice, that sort of thing)?

Any comments appreciated, you can mail me directly at wittmann@engr.wisc.edu
if I get enough response, I'll post a summary.

By the way, the man pages mention the 68010 and 68020 as CPUs that the
compiler is aware of, nothing on the 68030... seems odd.

Art

disclaimer: I disclaime!

rjn@hpfcdc.HP.COM (Bob Niland) (08/16/89)

re: wittmann@engr.wisc.edu (art wittmann) writes....

> I just got a 98248a FPA for my 9000/360.
> ...
> ...saw about a 10% performance increase.  

The recommended FPA for the 360/370 is the 98248B.  The 98248A was
optimized for the 330 and 350.  Offhand, I'm not sure if the 10% result
is typical for your configuration.

Regards,                                              Hewlett-Packard
Bob Niland        rjn%hpfcrjn@hplabs.HP.COM           3404 East Harmony Road
                  [hplabs|hpu...!hpfcse]!rjn          Ft Collins CO 80525-9599

irf@kuling.UUCP (Bo Thide') (08/17/89)

In article <5570266@hpfcdc.HP.COM> rjn@hpfcdc.HP.COM (Bob Niland) writes:
>re: wittmann@engr.wisc.edu (art wittmann) writes....
>
>> I just got a 98248a FPA for my 9000/360.
>> ...
>> ...saw about a 10% performance increase.  
>
>The recommended FPA for the 360/370 is the 98248B.  The 98248A was
>optimized for the 330 and 350.  Offhand, I'm not sure if the 10% result
>is typical for your configuration.
>

I had a 9828A for my 350 and saw a 100-250% performance increase in a
very floating-point oriented test.  When I upgraded to the 370 I also
changed to the 98248B (Dragon II) and saw a somewhat lower performance
increase.  This is probably due to the fact that the 33MHz 68882 in the
370 is much faster than the 20 MHz 68881 that I had in the 350 so the
difference between the coprocessor and the FPA is smaller in the 370.
Of course, the 370 + Dragon II is a faster floating point machine than
the old 350 + Dragon I but not as much as I had hoped.  I understand the
300 series FPAs are manufactured by Intel (?).  Why didn't HP choose to
replace Dragon I with a similar PFA as in the 9000/835 which is *much* faster?


   ^   Bo Thide'--------------------------------------------------------------
  | |       Swedish Institute of Space Physics, S-755 91 Uppsala, Sweden
  |I|    [In Swedish: Institutet f|r RymdFysik, Uppsalaavdelningen (IRFU)]
  |R|  Phone: (+46) 18-403000.  Telex: 76036 (IRFUPP S).  Fax: (+46) 18-403100 
 /|F|\        INTERNET: bt@irfu.se       UUCP: ...!uunet!sunic!irfu!bt
 ~~U~~ -----------------------------------------------------------------sm5dfw