Date: Tue, 18 Jun 1996 08:48:14 -0700 From: "Michael L. VanLoon -- HeadCandy.com" <michaelv@HeadCandy.com> To: "Eloy A. Paris" <Eloy.Paris@ven.ra.rockwell.com> Cc: hardware@freebsd.org, questions@freebsd.org Subject: Re: FreeBSD works with Cy486DLC processors? Message-ID: <199606181548.IAA16110@MindBender.HeadCandy.com> In-Reply-To: Your message of Tue, 18 Jun 96 09:13:02 -0400. <2.2.16.19960618093049.301ff69c@zeus.ven.ra.rockwell.com>
next in thread | previous in thread | raw e-mail | index | archive | help
>Well, I do not have an external cache. I was talking about the internal
>cache. That one is disabled. But anyway, what does the internal cache have
>to do with the mother board design? That is internal to the processor... The
>external cache is also disabled because I don't have one.
The CPU's internal cache requires the motherboard to help it with bus
snooping and invalidating addresses that another bus-master on the bus
writes.
I. e. without help, if a bus-master writes something to memory that is
also in the cache, the CPU has no idea that data has just become stale
without help from the motherboard. So now there is data in the cache
that is different from that same address' data in RAM. (Yes, I know
there are smarter processors, but AFAIK this is how the 486DLC does
it.)
-----------------------------------------------------------------------------
Michael L. VanLoon michaelv@HeadCandy.com
--< Free your mind and your machine -- NetBSD free un*x >--
NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3,
Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32...
NetBSD ports in progress: PICA, others...
Roll your own Internet access -- Seattle People's Internet cooperative.
If you're in the Seattle area, ask me how.
-----------------------------------------------------------------------------
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199606181548.IAA16110>