Re: Implementor support for the binary interchange formats
Date: Tue, 01 Mar 2011 11:34:44 -0500
To: stds-754 <stds-754@xxxxxxxxxxxxxxxxx>
From: Michel Hack <hack@xxxxxxxxxxxxxx>
Subject: RE: Implementor support for the binary interchange formats
Intel people should correct me if needed, but I was under the impression
that Itanium has hardware support for efficient software implementation
of binary128, and is one of the early machines to define what eventually
became the 2008 binary128 standard.
As for COBOL's FLOAT-SHORT, -LONG and -EXTENDED, I suspect they were
mapped to binary32, binary64 and Intel's binary80. Binary16 has been
defined as a low-precision compact storage format; I know of no uses,
but there may be some in the embedded-system space.
---Sent: 2011-03-01 16:45:00 UTC
Actually, Michel, it is the HP & Sun people who should
correct you. :-)
The floating-point type that we called binary128 in the
2008 standard is identical to the quad floating-point
type that was used both by HP in their earliest RISC
machine & Sun in some of theirs.
I was involved in defining quad for HP & I have become
friends with those involved in the same thing at Sun.
There is some friendly dispute as to who came first but
I like to say that we copied each other. While I don't
remember exact dates, I am sure I was working on what
we called IEEE quad prior to 1988. Probably as far back
as 1985 or 1986. I am less certain about that. The
machines ran at 8 MHz if that helps fix the date.
Both these 128 bit formats & Intel's 80 bit format were
considered instantiations of 754-1985's Double Extended.
Intel's being the smallest possible instantiation & ours
being the smallest instantiation aligned to a 64 bit
At the time I felt that the 128 bit types naturally made
more sense. But over the years I have come to discover
that making natural sense is overrated. The 80 bit
format has turned out to be useful as well.
Still we in the 754-2008 revision committee thought it was
time to bless the 128 bit format as basic with the name
binary128 lest some future architect decided to play games
with it. And we admitted both formats to a class of user
defined formats that we also blessed as conforming.
Alas, it was also necessary to admit Intel's newer 82 bit
format as acceptable. And it must be admitted that it
was first developed at HP before Intel bought it out.
Still, some people really like to push unnatural to the
P.S. - Oh, as for full hardware support, the first I am
aware of is a machine that was designed at HP Labs by
people we brought over from IBM in a computer architecture
that was eventually to be sold to Intel as Itanium. We
are more inbred than most of us like to admit. :-)