Date: Mon, 2 Jun 1997 16:34:26 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: dgy@rtd.com (Don Yuniskis) Cc: msmith@atrad.adelaide.edu.au, freebsd-hackers@freefall.FreeBSD.org Subject: Re: diskless hardware *design* suggestions Message-ID: <199706020704.QAA19821@genesis.atrad.adelaide.edu.au> In-Reply-To: <199706020647.XAA19653@seagull.rtd.com> from Don Yuniskis at "Jun 1, 97 11:47:59 pm"
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Don Yuniskis stands accused of saying: > > Yes. But, to be honest, I haven't looked at it in detail > as it's pretty minimalist (the SC400 is intended for use in > high end PDA's, etc. driving an LCD/pen interface). Use > of the display controller requires you to give up the 32bit > databus in favor of 16... Ah, understood. Amazing that Motorola have had dynamic bus sizing for the last decade or more... > > > Yes. Those NIC's that support DMA tend to be bus-mastering > > > themselves -- hence my problem! > > > > The Crystal parts do slave DMA, but that's generally too slow to be useful. > > If they'll push 32 bits at a time and aren't limited by things like > the ISA "standard" DMA rates, that could be quite usable since it > would eliminate the need for a separate buffer memory, etc. No, they are ISA devices, and as such are 16-bit only. > I'm suspecting that 1MB/s is probably less than ideal for some of the > applications I have in mind. I'd like to nail down the network > interface "once and for all" and not have to redesign it later, > etc. AMD's SuperNet2 parts look attractive but that's a sizeable > investment in silicon and driver development (and *definitely* > gobbles up too much real estate). I was hoping a 10Base2 > solution would be *very* appealing and keep me from digging > into some of the other options... (hmmm... what's that? > "Design by laziness"?? :>) Well, if 1M/sec is too slow, have you actually sized your throughput requirements, or are you just going on "feel"? 8) -- ]] Mike Smith, Software Engineer msmith@gsoft.com.au [[ ]] Genesis Software genesis@gsoft.com.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control. (ph) +61-8-8267-3493 [[ ]] Unix hardware collector. "Where are your PEZ?" The Tick [[
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