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From: aglew@ccvaxa.UUCP
Newsgroups: net.arch
Subject: Re: What's RISC all about ... REALL
Message-ID: <5100117@ccvaxa>
Date: Wed, 30-Jul-86 22:28:00 EDT
Article-I.D.: ccvaxa.5100117
Posted: Wed Jul 30 22:28:00 1986
Date-Received: Sat, 2-Aug-86 01:27:51 EDT
References: <278@fai.UUCP>
Lines: 22
Nf-ID: #R:fai.UUCP:278:ccvaxa:5100117:000:963
Nf-From: ccvaxa.UUCP!aglew    Jul 30 21:28:00 1986


>Hmmm.  It just occurred to me that the speed of main memory is a big
>factor in the opcode/microcode trade-off.  Could Vaxen have been designed
>with much slower main memory in mind?  (Or faster cache?)
>		Ronald O. Christian (Fujitsu America Inc., San Jose, Calif.)
>		seismo!amdahl!fai!ronc  -or-   ihnp4!pesnta!fai!ronc

The cost (both in dollars and in space) of memory also plays a factor.
I have a card (an old punch card - I scrounged several boxes when the site
I was working at finally threw out the keypunches) on my wall with this on
it:

    WOW! In the early 1970s, 8K of ROM = 8 bits of register.
    What a reason for microcode! [from one of Patterson's papers]

I'm waiting for this to happen again, probably in the early days of
optical computers.

Of course, you can always execute microcode from RAM...

Andy "Krazy" Glew. Gould CSD-Urbana.    USEnet:  ihnp4!uiucdcs!ccvaxa!aglew
1101 E. University, Urbana, IL 61801    ARPAnet: aglew@gswd-vms