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computers / comp.os.vms / Re: DEC VAX 8650

Re: DEC VAX 8650

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Subject: Re: DEC VAX 8650
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by: gah4 - Sat, 11 Feb 2023 18:46 UTC

On Thursday, February 9, 2023 at 4:35:22 PM UTC-8, Don North wrote:

(snip)

> "Fernando Cristino Colon Osorio is a Puerto Rican engineer, inventor, educator,
> and entrepreneur who is currently the executive director of the Wireless Systems
> Security Research Laboratory (WSSRL). In 1975 he was the primary architect of
> Digital Equipment Corporation (DEC) PDP 11/60 floating point unit. The FP11E
> incorporated the Newton-Raphson method as a mechanism to accelerate floating
> point division by a factor of 6X.

I suspect the algorithm that IBM used for the 360/91.

It is a favorite for discussing in books on pipelined processors.
Though you only use it if you already have a high speed multiplier.

The 360/91 does floating point double precision add in 2 cycles,
multiply in 3, single precision divide in 12, and double precision in 18.