Date: Wed, 14 Aug 1996 06:32:00 -0700 From: "M.R.Murphy" <mrm@Mole.ORG> To: msmith@atrad.adelaide.edu.au, ponds!rivers@dg-rtp.dg.com Cc: freebsd-hackers@freefall.freebsd.org, lakes!rivers@freefall.freebsd.org Subject: Re: Recap of sio weirdness, where to go from here... Message-ID: <199608141332.GAA22170@meerkat.mole.org>
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> Unless these parts are marked "PC16550DN" they are _not_ *actual* > 16550's. They may be a clone produced by another manufacturer, but as > has also been discussed here at great length (Where's Frank D. these > days?), this is _no_ guarantee that the part doesn't do something > funny. Close, no cigar. I have about 60 in Digiboards, HUB6's, and 2-port boards, all from National Semiconductor and all are marked "NS16550AFN" and "NS16550AN". No _silo_ interrupts from any of them, but I changed the FIFO_TRIGGER from FIFO_TRIGGER_14 to FIFO_TRIGGER_8 in sio.c. I wanted more time to service the interrupt and clear the FIFO at the expense of more interrupts. I think it works out to 8 character times plus 1/2 bit time rather than two character times plus 1/2 bit time. I think if they don't say "NS" and don't have the little squiggly logo, they're clones. I have 2 clone ports on a cheap IDE controller. They report that they are 16550's, but they'll only do 56KB. Not quite 16550's. -- Mike Murphy mrm@Mole.ORG +1 619 598 5874 Better is the enemy of Good
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