Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!hellgate.utah.edu!uplherc!wicat!meph!gsarff
From: gsarff@meph.UUCP (Gary Sarff)
Newsgroups: comp.arch
Subject: Re: SunMMU history
Message-ID: <00057@meph.UUCP>
Date: 24 Jan 91 21:26:01 GMT
References: <1991Jan19.133914.23871@bellcore.bellcore.com>
Reply-To: gsarff@meph.UUCP
Organization: WICAT Systems Inc., Orem Utah
Lines: 22

In article <1991Jan19.133914.23871@bellcore.bellcore.com>, mo@messy.bellcore.com (Michael O'Dell) writes:
>Various people have posted here recently expounding on the
>clear and obvious (to them) botches of the original SunMMU design.
>One thing to keep in mind is that Sun was shipping systems with
>virtual memory LONG, LONG before the 68881 was little more than
                                      ^^^^^ actually 68851
This is not a flame, we all knew what you meant. 8-)

>a "gee I wish I had" dream.  Because the mmu had to be done in random
>logic (asics and such weren't there then), it had to be simple,
>and if it weren't to introduce wait states, it had to be fast.
>The way to do that at the time was to use fast static RAMs and
>implement the direct lookup algorithm in hardware.  When originally done,

Someone out there in netland may remember WICAT also, 68K based systems
multiuser multitasking OS, protected address spaces, MMU made with fast
static ram, some gates, some pals, voila, hardware memory management, 4K
pages, because of the size of the static ram used.

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