Date: Sat, 8 Jun 1996 00:39:00 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com> To: Brett_Glass@ccgate.infoworld.com (Brett Glass) Cc: sef@kithrup.com, questions@FreeBSD.org, freebsd-hardware@FreeBSD.org Subject: Re: Which dual Pentium motherboard? Cyrix SMP? Message-ID: <199606080739.AAA13057@GndRsh.aac.dev.com> In-Reply-To: <9605078341.AA834195613@ccgate.infoworld.com> from Brett Glass at "Jun 7, 96 07:57:30 pm"
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> > However, EISA requires motherboard and NVRAM configuration for *all* of > > the cards, be they ISA or EISA. > > Nope. ISA cards work without configuration in an EISA system, so long as > there are no conflicts. This is because configuration files are not > available for most ISA cards. (Some manufacturers created "generic ISA > device" configuration files, but system integrators tended not to use them. > The systems still worked.) Correct, for _pure_ ISA cards. > > > If, as Rod suggested, the floppy controller is on an already-configured > > EISA card, and you move it to a different slot or different motherboard, > > you are quite likely to be hosed. > > Actually, this is generally NOT true. Even though it's an EISA card, the > floppy controller is usually just an ISA interface that's "coming > along for the ride" on the same physical board. It is usually enabled by a > jumper. Sometimes, the EISA configuration can DISABLE it, but on most > cards, the jumper is the only way of turning it on or off. This makes the card not a _pure_ EISA card. If it has resources on it that respond to I/O cycles that are not controlled by the EISA configuration parameters, the card is in violation of the EISA spec. Those cards that use a jumper _only_ to control the ISA floppy interface on them are not true EISA cards, but mixed ISA/EISA cards. Seems this is actually a better thing to do for floppy controllers though :-). > If you don't realize this, you can wind up with two conflicting floppy > controllers on the same IRQ, DMA channel, and I/O ports. This can cause > trouble. Yepp.... it's just not a pretty picture either way you dice it. Remeber, part of the idea of EISA was to eliminate jumper settings and go to a soft configure, but everyone seems to have cheated on this one :-(. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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