Date: Wed, 11 Nov 1998 17:35:53 -0500 From: "David E. Cross" <crossd@cs.rpi.edu> To: Mike Smith <mike@smith.net.au> Cc: Phillip Salzman <psalzman@gamefish.pcola.gulf.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: Kernel Hacking stuffs (Bidirectional Parallel Port) Message-ID: <Pine.SGI.4.05.9811111734450.2459-100000@o2.cs.rpi.edu> In-Reply-To: <199811112228.OAA05676@dingo.cdrom.com>
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On Wed, 11 Nov 1998, Mike Smith wrote: > There are several different (incompatible) ways of shifting > bidirectional data. > > The nibble mode you describe is the lowest common denominator. There's > also "true bidirectional" mode, where the 8 data lines are > open-collector outputs, so driving them high lets you listen to the > other end. Then there are the EPP 1.7 and EPP 1.9 modes, and ECP to > finish it all off. > > Ppbus either supports or will support all of these, depending on the > capabilities of your hardware. You can see the nibble and "true" modes > in action in the 'vpo' driver. Ahh, this is what I was looking for. I had looked in lpt.c and nlpt.c (from the ppbus device directory). I will check out 'vpo' now, thank you :) -- David Cross To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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