Date: Fri, 13 Oct 2000 13:53:52 -0700 (PDT) From: Jin Guojun (DSD staff) <jin@george.lbl.gov> To: ragnar@sysabend.org, richard@cogsci.ed.ac.uk Cc: hardware@FreeBSD.ORG, jin@george.lbl.gov, thebs@smithconcepts.com, thebs@theseus.com Subject: Re: K7V problem? <- Make sure DIMM is in slot 1 Message-ID: <200010132053.e9DKrqi24279@portnoy.lbl.gov>
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On Fri, 13 Oct 2000 Jamie Bowden <ragnar@sysabend.org> wrote: } :> I'm not aware } :> of what exactly is meant by 'registered DIMMs', could someone explain. } : } :I think it means "having registers" :-) } : } :According to http://www.memoryx.net/128rpc133ecc.html: } : } : Registered means the module has a type of buffering. This allows more } : modules to run stably in a system. To use registered dimm, your } : mainboard must support registration and you can not mix registered } : and non registered memory. } } I have no idea if the DIMM is registered or not. The memory supplier you } point to above sells both reg'd and unreg'd 256M DIMMs, so size is not an } indicator. Looking at the price difference, I doubt I have a reg'd DIMM. } I'd also think if I did, nothing would work, not just FreeBSD. Not for this case, but reverse one. 'registered DIMMs' means buffered DIMMs. buffered DIMM is for EDO type memory, and registered DIMM is for SDRAM. They are the same term in different technologies. Normally, unbeffered DIMM looks like -- | | | | | | | | non-parity | | | | | | | | | parity buffered/registered DIMM looks like -- | | | | -- | | | | non-parity | | | | -- | | | | | parity Each line represents a memory chip. Another way to look at this is the notch location. unbuffered DIMM module has this notch away from 20 pin (close to 60 pin) side. buffered DIMM module has this notch in the middle between 20 pin and 60 pin. Putting a unbuffered DIMM in buffered memory controller will not work at all. Putting a buffered/registered DIMM in an unbuffered memory controller may or may not work depending on the chip feature (double buffered signal). This is similar to putting some good 70ns memory to a 60ns system and the system will work no problem. By putting random 70ns memory chip into a 60ns system may have marginal work, or may not work at all. If you have registered DIMM, this probably is a case. The only controller known to work with registered and unbuffered 256MB DIMM is the intel BX-440 chip. All those 8## chip designed to work different memory modules between DIMM and RIMM do not seem work well at this point. I did not catch your original message. If your system works under other O.S., but FreeBSD, I would like to know how can we solve the problem. -Jin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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