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Newsgroups: comp.unix.bsd Path: sserve!manuel!munnari.oz.au!uniwa!cujo!marsh!cproto From: cproto@marsh.cs.curtin.edu.au (Computer Protocol) Subject: Re: (386BSD) Modems and com ports Message-ID: <cproto.714407748@marsh> Keywords: internal or external? Sender: news@cujo.curtin.edu.au (News Manager) Organization: Curtin University of Technology References: <1992Aug20.171557.30071@watson.ibm.com> <1992Aug20.213721.4548@gateway.novell.com> <x__nl1q.hasty@netcom.com> Date: Fri, 21 Aug 1992 14:35:48 GMT Lines: 40 hasty@netcom.com (Amancio Hasty Jr) writes: >I think that if the com driver is strap to interrupt levels less than >disk level, then under heavy I/O activities the com drivers will drop >characters. If the com drivers is split into two parts: >(a) a routine at high level interrupt level less than splhigh and at > least as high as diskio that just collects the characters and queues > the requests to be processed at a lower priority. >(b) essential the same com driver that de-queues the request from its > higher level routine >If such a scheme is not implemented, it is conceivable that the system >may lock out spltty interrupts long enough for the uart to drop characters. >The above outlinde strategy has been implemented in Unix systems for pcs >with good results for instance the system being able to drive four >com ports at 9600 without dropping a single character. >Cheers, >Amancio Hasty I couldn't agree more. Here at Computer Protocol we have developed 68000 based boxes running at whimpish 10 MHz with 4 simple Zilog 8530 serial controler chips providing 8 synchronous ports. It easily supports 8 full duplex X.25 links at 9600 b/s. Compare that to a 486 at 33MHz and with only one 9600 b/s port. Unless you do something really silly, it shouldn't be a problem. 386BSDs com driver sucks, it can't keep up. I would write a new com driver from scratch using the strategy posted by Amancio but I haven't got the time. It's definitely the right way to go. If nobody else voluntiers then I might risk a divorce and do it at home. Regards - Tibor Sashegyi (cproto@abel.cs.curtin.edu.au)