[comp.sys.hp] I plan to buy an HP/720. Is 16 Mb RAM enough ...... ?

karim@ecsvax.uncecs.edu (Omar A. Karim) (06/26/91)

I have looked at an IBM/320 and an HP/720 for possible purchase.
For reasons of FORTRAN numbercrunching speed, I am leaning toward
the HP right now. For my programs (molecular dynamics) the HP
ran 1.6 faster than IBM. By the way, the -O option in HP f77
altered the result of one of my subroutines. I had to be content
with the +O1 for that routine.
 
In any case, what I would like to know is whether a 16 Mb RAM
420 Mb disk, 19 in color and DAT drive would all work together
under HP-UX... mainly Vue and the 16 Mb. Naturally the demo machine
I had here was with 32 Mb RAM and that worked fine. 
 
Bottom line: does HP-Vue compete with background FORTRAN memory-resident
 numbercrunching jobs? Does it WIN if RAM is 16 Mb?  I am sure I 
cannot afford the 32 Mb RAM without sacrificing the color monitor. 
 
Any remarks stemming from experience will be appreciated. 
 
Thanks
Omar A. Karim
Department of Physics
UNC-Wilmington

campbelr@hpcuhe.cup.hp.com (Bob Campbell) (06/27/91)

> I have looked at an IBM/320 and an HP/720 for possible purchase.
> For reasons of FORTRAN numbercrunching speed, I am leaning toward
> the HP right now. For my programs (molecular dynamics) the HP
> ran 1.6 faster than IBM. By the way, the -O option in HP f77
> altered the result of one of my subroutines. I had to be content
> with the +O1 for that routine.

I hope that this behaviour was reported to out compiler lab.  If there
is a problem, I know they would like to understand it.
 
> In any case, what I would like to know is whether a 16 Mb RAM
> 420 Mb disk, 19 in color and DAT drive would all work together
> under HP-UX... mainly Vue and the 16 Mb. Naturally the demo machine
> I had here was with 32 Mb RAM and that worked fine. 

Well, I assume it is too late to just pull out 16 Mb and run your
program.  The thing that is best and worst with VUE is that it makes
it easier for you to do more things at once, using more resources.
If your program does not need 8 Mb of memory for itself, you probably
will not thrash.  Also, you do not have to use VUE.  You can easily
run X straight or reconfigure/selectivly use VUE to use less memory.
 
> Bottom line: does HP-Vue compete with background FORTRAN memory-resident
> numbercrunching jobs? Does it WIN if RAM is 16 Mb?  I am sure I 
> cannot afford the 32 Mb RAM without sacrificing the color monitor. 

Well, it is easier to add more memory later than to get another set
of graphics hardware.  If color is important to you, I'd get it now.
When you really need every bit of performance, just kill off everything
else that doesn't need to be running.
 
> Any remarks stemming from experience will be appreciated. 

I would also suggest you talk to your sales rep on the ability to
trade in the color graphics for greyscale and more memory.  If they
can't satisfy you that way, ask to run your software on a 16 Mb
configuration.
 
> Thanks
> Omar A. Karim
> Department of Physics
> UNC-Wilmington

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Bob Campbell                Some times I wish that I could stop you from
campbelr@cup.hp.com         talking, when I hear the silly things you say.
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