Date: Sun, 1 Jun 1997 13:53:49 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: dgy@rtd.com (Don Yuniskis) Cc: msmith@atrad.adelaide.edu.au, dgy@rtd.com, freebsd-hackers@freefall.FreeBSD.org Subject: Re: diskless hardware *design* suggestions Message-ID: <199706010423.NAA11598@genesis.atrad.adelaide.edu.au> In-Reply-To: <199705312113.OAA10085@seagull.rtd.com> from Don Yuniskis at "May 31, 97 02:13:56 pm"
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Don Yuniskis stands accused of saying: > > Haven't yet decided since that would be a daughterboard, > anyway. BTW, the SC400 includes support for direct drive > of an LCD display, etc. It *could* be kludged to drive > a CRT with a small effort... ... so it has an onboard video controller of some sort? > > DMA is not common with NICs. Shared memory (usually controlled by > > the NIC) and programmed I/O are the norm. > > 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. > AMD's devices that are interesting all want to be bus masters. > Some of SMC's newer parts are somewhat appealing (10Base* > devices with integrated RAM, etc.). Still no clear cut "winners", > though... it's unfortunate that all the [34]86 MCU's have either > missing DRAM controllers or poor/nonexistent support for > bus mastering (obviously because they would have to drive the bus > back *into* the MCU core...) TBH, unless you desperately need 100Mbps ethernet performance, a PIO-only solution using an 8390-family part (private SRAM) or even one using shared memory (remember that the 8390-family parts take most of the work out of arbitrating for the RAM, check the datasheets) will give you a very high-performance 10Mbps solution at low cost/complexity. The "smaller" solutions like the SMC and Crystal parts are short on features (less packet RAM most significantly), and IMHO they're not suitable if performance is an issue. > thx! > --don > -- ]] 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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