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| Author | 8600 Refuses to Boot (Read 2250 times) | ||||||||||||||
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dpaanlka
1024 MB  Posts: 1646 
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on: June 19, 2007, 02:57
I recently re-built an 8600/200 from a bunch of parts lying around, including a 10gb hard drive, a SCSI ribbon from another machine, and various RAM and other stuff. The 8600 has two SCSI busses on the motherboard, I assume one is for hard drives and one is for opticals but I can't be sure. The bus that the hard drives were originally attached to no longer seemed to be working, as my drives wouldn't be recognized when I booted from a CD-ROM. So I just attached both the hard drive and the CD-ROM drive to the same ribbon on the second SCSI bus. Twice now, this month, it has crashed while doing something trivial, and after restarting, refused to boot. It shows the classic Mac icon for a second, as if it has found a working system folder, but then it turns back into a blinking question floppy, as if it changed it's mind. Booting from a Mac OS CD, I browsed through the System Folder to try and determine why it wouldn't boot. I can still see all the files on the hard drive just fine. I just noticed, however, that whenever I try to open the System suitcase inside the System Folder (which normally should be open-able) I get an Error -199 "map inconsistent with operation" error. What might be going on here? Is this a drive issue? Possibly with my bus arrangement? Or might this just be a drive failure? Or even worse, a motherboard failure? |
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wove
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1024 MB Posts: 1363
Reply #1 on: June 19, 2007, 05:27
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The 8600 in a stock configuration has 2 SCSI busses. One is the internal SCSI buss and it is faster. The other is the external SCSI buss and it is slower. They are Buss 0 and buss 1. It is possible for each to have 8 device numbers, so there can actually be 16 SCSI devices attached to the 8600 (less of course the MB controller which occupies each chain.) The normal route for the SCSI cable is to start on the MB go up the back of the device bays and end at the hard drive on top of the power supply. The hard drive on the top of the power supply would in a stock configuration be set at device 0 and terminated. The CD ROM would be device 3, and if present the Zip Drive would be device 5. You can certainly use both SCSI chains internally, but if you do you will need to take into account termination issues. Not only would the last device on the chain internally need to be terminated, but the external SCSI port would be a fork in the external SCSI so you would need to have a terminator on the SCSI port even if no other device is present. bill
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dpaanlka
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1024 MB Posts: 1646
Reply #2 on: June 19, 2007, 08:54
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I don't recall ever having to manually terminate any PCI-based Mac.
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wove
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1024 MB Posts: 1363
Reply #3 on: June 20, 2007, 03:59
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The symptoms you mention in the first post almost invariably point to a termination problem. That of course does not rule out the possibility of other causes. Issues effecting termination include: Not having the last device on the chain terminated. Not having the last device on the chain plugged into the last connector on the ribbon cable. If there are more connectors on the cable than their are devices, the extra connectors must fall in the middle not hanging off the end. Having more than one device terminated. Several Mac computers have the CD Drive as the last device on the SCSI chain and it is terminated. If pulled from such a configuration and put into the middle of the chain, the drive will need to have its termination removed. Regardless of any causes or reasons, the loss of the internal SCSI buss on an 8600 has disastrous effect on the 8600 and its abilities. The internal buss is tied into the MESH controller, which gives it direct access to the PCI devices, the video sub system and the main system buss. Much like the SCSI on the Beige G3s, the external buss is designed for less data intensive devices such as scanners, and zip drives and not really designed to handle the demands of resource intensive tasks such are recording video etc. If I intended to put the 8600 into productive use, I would replace its motherboard. bill
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