Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!sco!seanf
From: seanf@sco.COM (Sean Fagan)
Newsgroups: comp.arch
Subject: Re: [really, CISC-to-the-max]
Message-ID: <3206@scolex.sco.COM>
Date: 21 Aug 89 07:15:14 GMT
References: <38139@stellar.UUCP> <24889@winchester.mips.COM> <846@babbage.acc.virginia.edu> <21353@cup.portal.com> <303@gvlv2.GVL.Unisys.COM>
Reply-To: seanf@sco.COM (Sean Fagan)
Distribution: usa
Organization: The Santa Cruz Operation, Inc.
Lines: 22

In article <303@gvlv2.GVL.Unisys.COM> kleonard@gvlv2.GVL.Unisys.COM (Ken Leonard) writes:
>There was at least one model/series/family of IBM machines that _DID_HAVE_
>hardware square root--the 70x0/STRETCH.
>In fact, it was _REAL_HARDWARE_ sqrt, not microcoded nor some funny use of
>the divider hardware.  The sqrt unit was implemented primarily with tunnel-
>diode gates and (at the time) a minimum amount of fastest available
>transistors.

Cray-2's, at least, have sqrt and 1/sqrt (no divide, of course; but they do
have reciporocal [sp?]), all in hardware.  God, aka Seymour Cray, doesn't
believe in microcode.  Then again, he also doesn't believe in virtual memory
(yes, it does slow things down; so does having to wait noticeably while one
extremely large application gets swapped out so that smaller ones can run).

Cray-1's and X-MP's don't have them, I believe; they seemed to be new with
the 2.  If memory serves me, the little instruction-set summary I got this
out of also showed a sqrt table in the functional-unit diagram...

-- 
Sean Eric Fagan  |    "[Space] is not for the timid."
seanf@sco.UUCP   |             -- Q (John deLancie), "Star Trek: TNG"
(408) 458-1422   | Any opinions expressed are my own, not my employers'.