Date: Thu, 31 Oct 1996 11:56:39 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: kuku@gilberto.physik.rwth-aachen.de Cc: gjennejohn@frt.dec.com, questions@freebsd.org, current@freebsd.org, isdn@muc.ditec.de Subject: Re: Any ISDN-BRI cards work under FreeBSD? Message-ID: <199610311856.LAA25769@phaeton.artisoft.com> In-Reply-To: <199610311454.PAA05342@gilberto.physik.rwth-aachen.de> from "Christoph Kukulies" at Oct 31, 96 03:54:32 pm
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> > > done it yet. They currently only run single channel connections (you > > > can have two different connections to different destinations). The > > > theoretical maximum throughput is 8 kB/s (64,000 bps), which is > > > somewhat less than the theoretical maximum of the 115.2 kbps lines > > > (11.52 kB/s). > > Why do you divide by 8 in the one case and by 10 in the other? My guesses: 8) 8*8k = 64k; conversion is for sync framing 10) 1 start + 8bits + 1 stop = 10bits; conversion is for async framing A more interesting question might be 64k + 64k = 128k. 128k != 115.2k. Here the answer is that the max PC port rate is 115.2k (unless you get a decent [non-Intel] UART serial board or buy a card from Dennis). So the conversion from sync to async is internal to the device, and is limited by the bit rate of the device-to-computer interface. This is the general problem with externally interfaced serial devices. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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