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Xref: sserve comp.os.linux.development:19167 comp.os.linux.misc:29434 comp.os.386bsd.questions:14373 comp.os.386bsd.misc:4054 sci.electronics:83852 Newsgroups: comp.os.linux.development,comp.os.linux.misc,comp.os.386bsd.questions,comp.os.386bsd.misc,sci.electronics Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!osuunx.ucc.okstate.edu!newsfeed.ksu.ksu.edu!moe.ksu.ksu.edu!crcnis1.unl.edu!wupost!uwm.edu!spool.mu.edu!howland.reston.ans.net!pipex!sunsite.doc.ic.ac.uk!uknet!info!iialan From: iialan@iifeak.swan.ac.uk (Alan Cox) Subject: Re: 16550 detection Message-ID: <Cz0oIy.K7p@info.swan.ac.uk> Sender: news@info.swan.ac.uk Nntp-Posting-Host: iifeak.swan.ac.uk Organization: Institute For Industrial Information Technology References: <MICHAELV.94Oct31211019@MindBender.HeadCandy.com> <TYTSO.94Nov1182557@dcl.mit.edu> <199411032154.NAA12270@exit.com> Date: Wed, 9 Nov 1994 20:20:58 GMT Lines: 33 In article <199411032154.NAA12270@exit.com> fmayhar@netcom.com writes: >very useful. You may say that such speeds are unrealistic, but with >v.34 and compression, throughputs of 115200 should become fairly common >on compressible data, and with ISDN you need the higher rates, since >you'll be running at up to 128kbps uncompressed. Without that 1024-byte With ISDN you need something better than a UART. You are normally looking at ethernet like block I/O interfaces. >Well, maybe. But you're expecting to use it at low data rates interactively. >I'm expecting to use it at much higher rates, and/or as a part of a network. >Sure, large FIFOs are overkill at 38400 bps, but at 57600 bps (the speed >I use at the moment) and better those FIFOs begin to look more like buffers >on a networking interface card. Indispensable. Its worth noticing high bandwidth 64 channel serial boards tend to run on a timer empty of the queue every clock tick not on anything more complex. With high data rates its simply not worth the hassle of handling bytes as they arrive. >I disagree. At the data rates I mean to use, the large FIFO and DMA >capability will mean a *greatly* reduced load on an already overtaxed >CPU. At $10 for a single-port card (at Computer City a couple of DMA is of dubious value (can anyone say 'CACHE'). For the kind of things a fast port is using block I/O will be faster until you get to extreme (Mbits/second) speeds. Alan -- ..-----------,,----------------------------,,----------------------------,, // Alan Cox // iialan@www.linux.org.uk // GW4PTS@GB7SWN.#45.GBR.EU // ``----------'`----------------------------'`----------------------------''