mjkobb@mit-amt.MEDIA.MIT.EDU (Michael J Kobb) (12/13/89)
Greetings, Ready for a stupid question? I just received my new LaCie hard disk, and I plugged it into my Mac Plus. Since the LaCie has the small SCSI connectors, I put it first in the chain, and chained my GCC HyperDrive FX/20 off of it. The HyperDrive's SCSI address is 6; the LaCie's is 1, so the Mac booted from the HyperDrive. Then, I wanted to test the system on the LaCie, so I shut down and turned off the HyperDrive. With the HyperDrive off, the system wouldn't boot. I can only surmise that this is the result of improper termination. The LaCie has internal, and (I suppose) automatic termination. The FX/20 requires one of the blocks. The question: does the block go in the unused SCSI connection on the last device in the chain, or between the cable and the drive? The manual for the FX/20 had conflicting info, and the LaCie didn't come with an installation manual at all! Thanks, --Mike
russ@key.COM (Russell Donnan) (12/14/89)
In article <1204@mit-amt.MEDIA.MIT.EDU> mjkobb@media-lab.media.mit.edu (Michael J Kobb) writes: >and turned off the HyperDrive. With the HyperDrive off, the system wouldn't >boot. I can only surmise that this is the result of improper termination. What you need to do is boot up with both drives, go into the startup device cdev, and select the OTHER drive. This is really selecting the SCSI id of the boot device. Macs boot off SCSI id 0 by default, but can easily be changed by this cdev. BTW, my manual shows that BOTH drives need to be terminated. You need to terminate the beginning and the end of the SCSI chain. Hope this helps! -Russ -- Russ Donnan (415) 623-2121 Amdahl Corporation, Key Computer Laboratories, Fremont, CA, USA russ@key.amdahl.com, ...!{pacbell,sgi,amdahl}!key!russ -To capture the essence of an opinion takes but one lawyer.
dplatt@coherent.com (Dave Platt) (12/14/89)
In article <1204@mit-amt.MEDIA.MIT.EDUmjkobb@media-lab.media.mit.edu (Michael J Kobb) writes: > Ready for a stupid question? There are very few stupid questions. Yours isn't one. Getting multi- vendor SCSI-bus configurations to work is a bit of a black art sometimes. > I just received my new LaCie hard disk, > and I plugged it into my Mac Plus. Since the LaCie has the small SCSI > connectors, I put it first in the chain, and chained my GCC HyperDrive > FX/20 off of it. The HyperDrive's SCSI address is 6; the LaCie's is 1, > so the Mac booted from the HyperDrive. Then, I wanted to test the > system on the LaCie, so I shut down and turned off the HyperDrive. > With the HyperDrive off, the system wouldn't boot. I can only surmise > that this is the result of improper termination. Yup. > The LaCie has > internal, and (I suppose) automatic termination. "Internal" I'll believe. I'm not sure I believe "automatic" (a terminator which senses whether it's needed, and connects or disconnects itself on that basis). I could be wrong, of course ;-). > The FX/20 requires > one of the blocks. The question: does the block go in the unused SCSI > connection on the last device in the chain, or between the cable and > the drive? Most manuals seem to say that it should be placed between the cable and the last device on the chain. In practice, it works equally well when plugged into the unused SCSI port on the last device. In at least one case (my "stripped Bering" box containing a Teac tape-drive), it works *better* when plugged into the spare port... the terminator's female connectors (into which the cable would plug) don't seem to make good contact with the cable. > The manual for the FX/20 had conflicting info, and the > LaCie didn't come with an installation manual at all! Sigh. Here's the situation you're facing: 1) All terminators require electrical power to function properly. If you have an unpowered terminator on your bus, you probably won't be able to access any device on the bus. 2) All external (plug-in block) terminators receive their power from the SCSI bus. At least one device on the bus must provide this power... +5 volts to pin 25 on the 50-pin connector, I believe. 3) Internal terminators are normally designed to accept power from the device to which they are connected. Some of them (in better- designed devices such as the Teac tape mechanism) can also accept power from the SCSI bus, if the device to which they are attached is powered down. 4) The Mac Plus does not provide terminator power, due to power-supply limitations. The II, SE, and all machines in those families do provide terminator power. I'm not sure about the portable. 5) Your FX/20 does provide terminator power. Your LaCie apparently does not. So... if your FX/20 is powered on, its external terminator-block receives power, and everything works find. If you power the FX/20 off, its external terminator doesn't get any power, its external terminator jams the SCSI bus, and you can't access the LaCie. Possible solutions: 1) Leave the FX/20 powered on whenever you use your Mac. To boot from the LaCie rather than the FX/20, use the "Startup Device" cdev in the Control Panel, and select the LaCie. This will override the usual SCSI-bus search preference (0-6-5-4-3-2-1). If the LaCie is powered off, or doesn't have a bootable System on it, then the Mac will revert to the standard device-search and will boot from the FX/20 (usually). If you want to switch back to the "boot from the FX/20" mode, use the Startup Device cdev again. 2) Modify the LaCie chassis to provide terminator power... it's usually done by wiring the +5 power supply to the appropriate pin on the SCSI connector through a blocking diode and a 1-amp fuse. This will void your warranty, most likely. 3) Build yourself a dummy SCSI-bus device whose sole purpose is to provide terminator power. Hook it up at the end of the chain, after the FX-20. Plug the external terminator block into this device rather than into the FX-20. 4) Trade in your Plus for a more recent Mac which does provide terminator power. I suggest approach (1) as being the simplest and most hassle-free. -- Dave Platt VOICE: (415) 493-8805 UUCP: ...!{ames,apple,uunet}!coherent!dplatt DOMAIN: dplatt@coherent.com INTERNET: coherent!dplatt@ames.arpa, ...@uunet.uu.net USNAIL: Coherent Thought Inc. 3350 West Bayshore #205 Palo Alto CA 94303
hammen@jolnet.ORPK.IL.US (Robert J. Hammen) (12/14/89)
Just one correction (that I could find!) to Dave's otherwise excellent post regarding the fine art of Macintosh SCSI: the "Startup Device" cdev does NOT work on the Plus - it stores its info into PRAM available only on the SE, II, and later models. The Plus will boot from the highest numbered SCSI device. Robert Hammen | Technical Editor | Personal Publishing | hammen@ddsw1.mcs.com
hammen@jolnet.ORPK.IL.US (Robert J. Hammen) (12/14/89)
Once again: Startup Device does NOT work on the Plus. I also believe that
the comment regarding how the Mac boots ("Macs boot from SCSI id 0 by default")
is incorrect. My experiences with the Mac would indicate the following:
Mac Plus: boot from highest numbered SCSI device (6 -> 0)
SE, II, Portable: boot from disk set in "Startup Device" cdev and stored in
PRAM. Otherwise, boot from SCSI ID 0 (special cased, since this is the ID that
the standard Apple internal drives are set. One nice feature is that the Mac
will "wait" for a disk at ID=0 to spin up before it boots (the Rodime 140
internal in my II isn't ready before the Mac is, so it's nice that the Mac
waits for it :-)
Robert Hammen | Technical Editor | Personal Publishing | hammen@ddsw1.mcs.comephraim@kulla (Ephraim Vishniac) (12/16/89)
In article <2390@jolnet.ORPK.IL.US> hammen@jolnet.UUCP (Robert J. Hammen) writes: > >SE, II, Portable: boot from disk set in "Startup Device" cdev and stored in >PRAM. Otherwise, boot from SCSI ID 0. Here's something I've wondered about: A disk (SCSI device, in this case) isn't the same thing as a volume. You don't boot from a disk, but from a volume on the disk. But drive numbers for volumes are assigned dynamically at boot time. So what does "Startup Device" actually record? A SCSI ID? A drive number? If the former, which volume does it use, given a choice? If the latter, isn't that bogus? >Robert Hammen | Technical Editor | Personal Publishing | hammen@ddsw1.mcs.com Ephraim Vishniac ephraim@think.com ThinkingCorp@applelink.apple.com Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142 One of the flaws in the anarchic bopper society was the ease with which such crazed rumors could spread.
hammersslammers1@oxy.edu (David J. Harr) (12/17/89)
Ephraim Vishniac was wondering whether what the startup device CDEV recorded and whether it was a drive number or a SCSI number. Let me relate my experiences, which may shed some light on the subject (and then again, they may not:-)). I have an 80 Mbyte Quantum internal and a 152 Mbyte Miniscribe external that have had various (hard) partitioning schemes. At one time, I think I had three partitions on the 80 Mbyte and 4 on the 152. Since these were hard partitions, they would auto-mount and were, for all practical purposes, independent SCSI volumes. HOWEVER, if I put a system file on more than one of the partitions of a single drive, the Mac would ONLY boot from the first partition on the drive with a system. By "first", I mean the partition created first with the partitioning software that had a system. Also, whenever I would access the Startup Device CDEV, whichever drive had last been specified as the boot drive would have ALL of its partitions highlighted. This leads me to believe that the Startup Device works on SCSI number. Of course, I could be wrong. David --- I would have a fancy .sig down here in this space, but I used --- all my really rip-roaring, braindead ideas above in the post.