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From: jhc@mtune.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: Vax 86xx FBOX decision
Message-ID: <1041@mtune.ATT.COM>
Date: Fri, 27-Mar-87 22:21:48 EST
Article-I.D.: mtune.1041
Posted: Fri Mar 27 22:21:48 1987
Date-Received: Sat, 28-Mar-87 18:08:35 EST
References: <3431@cisunx.UUCP> <15735@sun.uucp>
Reply-To: jhc@mtune.UUCP (Jonathan Clark)
Organization: AT&T ISL Middletown NJ USA
Lines: 17

> DEC's response: 
> 	'all compiles would be sped up by 50%, because the link
> 	editor uses floating point to calculate virtual addresses.'

I can't verify that statement, and it sounds pretty damn unlikely to
me, but apparently the FBOX uses its spare time to do pre-calculations
of effective addresses in the instruction stream, and thus speeds up
the entire machine somewhat. Since this is at or under the microcode
level, it's hardly surprising that Guy didn't find too many references
to float or double in the source of ld. It may have been that the FBOX
is doing instruction stream pre-decode, I forget now, but either of
these sounds plausible.
-- 
Jonathan Clark
[NAC,attmail]!mtune!jhc

Albatross! Stormy petrel on a stick!