Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!ames!think!husc6!seismo!nbires!ico!isis!csm9a!japplega From: japplega@csm9a.UUCP Newsgroups: comp.os.minix Subject: Re: "Brooklyn Bridge" (115Kb serial i/o), slave cards, etc. Message-ID: <467@csm9a.UUCP> Date: Tue, 7-Jul-87 00:37:38 EDT Article-I.D.: csm9a.467 Posted: Tue Jul 7 00:37:38 1987 Date-Received: Sat, 11-Jul-87 16:09:17 EDT References: <227@amanue.UUCP> Organization: Colorado School of Mines Lines: 21 I know the people who wrote the original LapLink (and are currently sueing Traveling Software over the trademark) and a few weeks ago they showed me the code.... it's amazingly simple to get 115,000 baud.... they directly write to the 8250 and set a divisor latch at 1 and the hardware does the rest! The real trick is the routine to write to the 8250... it is a pointer to a byte of the file being transfered (which their Turbo Pascal program already moved into heap space)... they output a byte the inc the pointer... it only takes 8 cycles... oh yes they check the pointer against the end of the file... and they counted the number of bytes when they loaded it... I don't think it's practical for networking.... it requires all the CPU can give!!! and then every packet would have to be preloaded into a memory location prior to sending Joe Applegate - Colorado School of Mines Computing Center {seismo, hplabs}!hao!isis!csm9a!japplega or SYSOP @ M.O.M. AI BBS - (303) 273-3989 - 300/1200/2400 8-N-1 24 hrs. *** UNIX is a philosophy, not an operating system *** *** BUT it is a registered trademark of AT&T, so get off my back ***