From: Dave Horsfall <dave@esi.COM.AU>
Date: Wed, 23 Nov 94 16:41:02 PST
To: cypherpunks@toad.com
Subject: Re: Pentium bug and CRYPTO
In-Reply-To: <9411231326.AA11476@vail.tivoli.com>
Message-ID: <Pine.SUN.3.91.941124113849.14333G-100000@eram.esi.com.au>
MIME-Version: 1.0
Content-Type: text/plain


On Wed, 23 Nov 1994, Mike McNally wrote:

> The imprecision in floating point is a factor only if you choose to
> pay attention to it.  It is possible to use floating point all day
> long to do what are essentially integer calculations.  indeed, there
> have been CPUs (the CDC 6000 series come to mind) that have no integer
> multiply or divide instruction.  Instead, one used the floating point
> instructions and then extracted the result (carefully) from the
> mantissa.

Quite so - my mistake.  It's been a while since I last looked at FPUs...

> Floating point isn't magic, it's just microcode.  (Well, not in the
> CDC 6000 I guess...)

Indeed - Seymour Cray was proud of the fact that his CDC machines
did not use microcode - that's what made them so fast.

-- 
Dave Horsfall (VK2KFU) | dave@esi.com.au | VK2KFU @ VK2AAB.NSW.AUS.OC | PGP 2.6
Opinions expressed are mine. | E7 FE 97 88 E5 02 3C AE  9C 8C 54 5B 9A D4 A0 CD