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Difference between HP PA-RISC and IPF Itanium

Occasional Contributor

Difference between HP PA-RISC and IPF Itanium

Hello !

I was searching for documentation on difference in HP PA-RISC and IPF architectures.
Since HP 11i V2 supports both of them, I wanted some detailed information on difference between these two architectures.

Can anyone of you please guide me to websites where I can find such documents.

I din't find a specific one on HP site.

Thanks n Regards,
Sagar Shinde
Steven E. Protter
Exalted Contributor

Re: Difference between HP PA-RISC and IPF Itanium

Some websites


Java differences on the two architectures


One thing I know is that Ignite's make_tape_recovery function was not fully functional on the Itanium platform, though there are varying reports on that.

The current release of HP-UX v2 will install on either architecture, but the code base is different. HP-UX v3 is supposed to be unified code base, one code base running on both system types.

Steven E Protter
Owner of ISN Corporation
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Brian M Rawlings
Honored Contributor

Re: Difference between HP PA-RISC and IPF Itanium

Hi, Sagar. There are very large differences, but in a very real way, Itanium is a "son of PA-RISC". HP co-developed the Itanium with Intel, and much of the massive internal parallelism and high "work per clock cycle" came from HP technology, based on PA-RISC.

HP concluded that PA-RISC would become too expensive to continue to build, as it ramped up in power and transistor counts, and down in microstructure and gate sizes. Each new milestone meant a whole new fab for the processing, and a chip fab is an increasingly expensive thing to build. So, let somebody who builds chips for a living (and has to build newer better fabs anyway) build the follow-on chips. Plus, Intel needed a more powerful processor to get it to the 64-bit market, or so it thought at the time (now with AMD leading the charge on the low end, everybody's doing it).

It took way too long, but Itanium is finally achieving its potential. HP's Itanium based servers are leading most of the benchmarks involving Floating Point and transactional processing these days. The current PA-RISC versions are way behind Itanium in these admittedly imperfect power ratings. Here are some interesting web sites:


On this next one, the part you are looking for starts about half-way through it. A relatively concise history of the two processors, the similarities and differences, and the reasons for the change.


Hope this is of some use. --bmr
We must indeed all hang together, or, most assuredly, we shall all hang separately. (Benjamin Franklin)
Jeff Schussele
Honored Contributor

Re: Difference between HP PA-RISC and IPF Itanium

Hi Sagar,

There is quite a difference between PA-RISC & Itanium2 when it comes to booting.
This is because the the IA systems use teh EFI (Extensible Firmware Interface) as opposed to the PA ISL (Initial System Loader).
The EFI requires a FAT-32 filesystem instead of the PA's HFS filesystem. And as SEP alluded to - this is *why* one cannot boot a recovery tape on an Itanium system. You have to boot the Install DVD first & then extract the contents of the recovery tape. That and the fact that an IA boot disk is sliced as well - i.e. /dev/cWtXdYsZ - are *the* main differences. The above make the root/boot mirror procedure *much* different. Not necessarily harder - just radically different.

My $0.02,
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Kent Ostby
Honored Contributor

Re: Difference between HP PA-RISC and IPF Itanium

Here's more details on Itanium and HP's point of view as to its advantages:

"Well, actually, she is a rocket scientist" -- Steve Martin in "Roxanne"