> > Hello Nat, > > NH> He gave it to me without a terminator on it. I ran it for those > > 10+ years that way with no problems, as that's the way he > > apparently ran it. > > I'm guessing that either a) the external disk was terminated inside > the box somehow or b) it was indeed unterminated, but your grandfather > got lucky in that it did not cause noticable problems.
So I got lucky on a daily basis for *ten years*? And then, coincidentally, the day I moved it to the Classic II my luck ran out? :) > > NH> I moved the drive over to my Classic II. > > It's possible that a Mac Plus is more forgiving of incorrect > termination than a Classic II (the newer machine almost certainly > pushes its SCSI bus faster, making timing more critical). > OK, I can see that. > A SCSI bus should be terminated at each physical end (and only there, > ignoring for a moment 16-bit 'wide' SCSI busses that you're not going > to find on a Plus or Classic II). The Mac is at one end of the chain > and terminates that one, so you only have to worry about the other > end. If you can find someone locally who is familiar with SCSI gear, > they should be able to check for you whether the drive is terminated. > I don't know anyone who knows anything about old SCSI stuff. That's why I'm asking here. :) > At the same time, they can check the SCSI ID: if the Classic II has > an internal hard disk, it's important that your external drive is set > to a different ID. The internal may be set to ID 0, the Mac will use > ID 7 for itself, if you have nothing else attached, there's a good > chance that ID 1-6 are available. The SCSI ID was the first thing I checked. The disk is set for SCSI ID 2 which shouldn't cause any conflicts with anything. That's what it's been set at as long as I've owned it. > > NH> Not owning any documentation on this, I go with the > > distributor's recommendation and pick up an "active" terminator. > > Whatever the hell *THAT* means. > > As I understand it, active terminators include a voltage regulator > that uses the termpwr signal from the bus to provide 'better' > termination than old-fassioned passive terminators. The catch is that > not all Macs supply the termpwr that an active terminator needs. Try > an inexpensive passive terminator (which should be adequate for the > kind of SCSI found on compact Macs), but only once you're sure the > drive is not already terminated. Like I said above, I don't know anyone who knows anything about these old SCSI systems. My second thought was to try to find information online about the drive itself, to see if maybe there was some documentation on the jumpers and/or if the drive is already terminated. The drive is an old 40-meg Conner something-or-other. I went to the Seagate website, and attempted to download the 5+ megabyte Adobe Acrobat file containing old Conner drive specs, but I got an error when I attempted the download. Google searches turn up nothing on Conner drives, aside from places to purchase them. So that takes me back to square one. > > It is also possible that the drive itself has stopped working, which > would be a nice opportunity to upgrade the enclosure with a larger > drive. > Let's say this is the case. Can I stick virtually any old SCSI drive in there and have it work with the hardware in the enclosure? And also, would the drive still spin up and report make/model information if it had stopped working? > I hope that this helps. > - Andy. > Yes, thank you for the explanation on the different types of terminators. I will attempt to find a passive terminator and see if that makes a difference. But one of my big questions still remains unanswered: what actually HAPPENS when a drive is terminated incorrectly? No problems at all in certain cases, intermittent problems, or permanent hardware damage? Has anyone here ever known an incorrectly terminated drive to suddenly become useless? Moreover, what are "phase errors" and "mode sense" errors? Thanks, Nat ------------ Nat Hall [EMAIL PROTECTED] ------------ -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
