Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: ABI and growth
Message-ID: <1990Jan16.173346.2154@utzoo.uucp>
Organization: U of Toronto Zoology
References: <6186@celit.fps.com> <2020@crdos1.crd.ge.COM>
Date: Tue, 16 Jan 90 17:33:46 GMT

In article <2020@crdos1.crd.ge.COM> davidsen@crdos1.crd.ge.com (bill davidsen) writes:
>  This is an old problem. The VAX gets around some of it by allowing
>"writable control store" (users defined microcode for certain
>instructions). A friend did a master's thesis based on implementing an
>FFT instruction in microcode. It was almost twice as fast as doing it
>with discrete instructions.

Which is actually fairly impressive, since the VAX WCS seems to have been
an afterthought and there was substantial overhead involved in getting to
it.  I guess his FFT instruction did enough work to amortize the overhead
pretty well.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu