There are several IRIX64 operating systems:

$ hinv -c processor
64 300 MHZ IP27 Processors
CPU: MIPS R12000 Processor Chip Revision: 2.3
FPU: MIPS R12010 Floating Point Chip Revision: 2.3
$ uname -aR
IRIX64 fcdfsgi2 6.5.19f 01100601 IP27
$

$ hinv -c processor
28 194 MHZ IP25 Processors
CPU: MIPS R10000 Processor Chip Revision: 3.1
FPU: MIPS R10010 Floating Point Chip Revision: 0.0
$ uname -aR
IRIX64 cdfsga 6.2 03131016 IP25
$


The following header lines retained to effect attribution:
>Date: Wed, 03 Mar 2004 18:10:13 +0000 (GMT)
>From: Joseph Michaud
>Subject: Re: 64-bit Pro/E
>To: info-iris-misc@ARL.ARMY.MIL
> hepa1.fnal.gov
>X-Spam-Level:


>In article , hamei wrote:


>> http://www.ptc.com/products/proe/64bit_faq.htm


>> 3. What platforms will support Pro/ENGINEER 64-bit and when will
>> they be available?


>> For the UNIX environment, the currently supported platforms include
>> Alpha UNIX True64 (which will no longer be supported after Release
>> 2001) and both Sun and HP platforms as of Release 2001 datecode 2001280.
>> Effective with the Pro/ENGINEER Wildfire Release, a 64-bit version for
>> SGI UNIX platforms (Pro/ENGINEER Machine Type sgi_elf4) will be available
>> in place of the existing 32-bit SGI UNIX versions (Pro/ENGINEER Machine
>> Type sgi_mips4). For the Windows environment, a future datecode of
>> Pro/ENGINEER Wildfire will be supported with Windows XP 64-Bit Edition
>> and the Intel Itanium2 processor. The 64-bit Windows platform of
>> Pro/ENGINEER Wildfire will be available in the fourth quarter of 2003.
>> ...
>> Anyway, it looks like there *is* a 64-bit Irix version ? Or was this
>> just conjecture ?


>Yes, there really is a 64-bit IRIX version. Works just fine.


>Joe


>Joseph Michaud - SGI Apps Eng 978-562-8894 x483-8894 jmichaud@sgi.com


Randolph J. Herber, herber@fnal.gov, +1 630 840 2966, CD/CDFTF PK-149F,
Mail Stop 318, Fermilab, Kirk & Pine Rds., PO Box 500, Batavia, IL 60510-0500,
USA. (Speaking for myself and not for US, US DOE, FNAL nor URA.) (Product,
trade, or service marks herein belong to their respective owners.)