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From: michaelv@MindBender.HeadCandy.com (Michael L. VanLoon)
Newsgroups: comp.unix.bsd
Subject: Re: HELP: installing netbsd+64mb RAM+adaptec
Date: 11 Nov 1994 20:30:02 GMT
Organization: HeadCandy Associates... Sweets for the lobes.
Lines: 40
Message-ID: <MICHAELV.94Nov11143004@MindBender.HeadCandy.com>
References: <1994Nov11.071053.26169@slate.mines.colorado.edu>
<1994Nov11.071527.130451@slate.mines.colorado.edu>
<39vogs$78p@dagny.galt.com>
NNTP-Posting-Host: mindbender.headcandy.iastate.edu
In-reply-to: alex@pc.cc.cmu.edu's message of 11 Nov 1994 12:36:43 GMT
In article <39vogs$78p@dagny.galt.com> alex@pc.cc.cmu.edu (alex wetmore) writes:
Ade Barkah (mbarkah@slate.mines.colorado.edu) wrote:
> I'm trying to install NetBSD 1.0 via floppies to my system.
> This machine is a DECpc 486 class machine, 64 megabytes
> of memory, with a 1 gigabyte SCSI drive attached an
> Adaptec SCSI host adapter (1542 series.)
NetBSD doesn't support DMA transfers on the ISA bus on machines with more
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
than 16 megs. You can use a VLB or EISA based SCSI controller (in 32-bit
^^^^^^^^^^^^
mode) and things should work.
Just a quick point of clarification. It's the ISA bus itself that
can't do DMA past 16MB of RAM. This is a physical limitation of the
brain-dead bus, not of NetBSD. EISA, VLB and PCI don't have this
limitation.
FreeBSD has bounce buffers which solve the problem. You get a slight
performance hit, but it will work on your system. FreeBSD-2.0-ALPHA just
came out yesterday.
What FreeBSD has is a hack to fix the ISA bus behavior. A necessary
hack because of the Neanderthal design of the ISA bus. But a hack,
regardless. This hack will also make its way into NetBSD post-1.0,
but doesn't currently live in NetBSD-1.0.
Your options are to buy a better SCSI card that uses PCI, EISA, or VLB
(recommended, just for sheer performance and usability reasons,
whether you use NetBSD or FreeBSD [or Linux]). Or, to use FreeBSD. I
believe FreeBSD-1.1.5 has the bounce-buffer code for ISA DMA.
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Michael L. VanLoon michaelv@HeadCandy.com michaelv@iastate.edu
Free your mind and your machine -- NetBSD free un*x for PC/Mac/Amiga/etc.
Working NetBSD ports: 386+PC, Mac, Amiga, HP300, Sun3, Sun4c, PC532
In progress: DEC pmax (MIPS R2k/3k), VAX, Sun4m
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