I spent most of today undoing the hanging of a passive terminator on the end of the scsi 50 pin cable and redoing what I had done before. I did not have another passive terminator and it did not seem that termination was the issue as everything worked at first. On redoing the setup with (for newcomers) my 9 gig Seagate Barracuda, I kept getting the message that, (this was after initializing and mounting the 9 gig drive) and I paraphrase, I would need a 68040 cpu as the 68030 did not do volumes over 4 gigabytes. I have a 68040 card on order and expect its arrival shortly together with the Asante device to plug it into. However I cannot get an answer from our friend Gamba with regard to obtaining the needed right angled connector. If there is another source of these I would appreciate finding the address.
It was so close and tantalizing. The computer read and saved the system I put on it . But it just would not remount it.
If it wasn't so much fun taking the SE/30 apart and putting it back together I might have gotten a bit steamed. C'�st la guerre.
On Saturday, December 27, 2003, at 08:19 PM, Jeff Walther wrote:
At 15:00 -0500 12/27/2003, Compact Macs wrote:
From: "Brandon Davis" <[EMAIL PROTECTED]> Date: Fri, 26 Dec 2003 19:55:27 -0800
SCSI 50-Pin M-F Internal Passive Terminator #3449322827 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3449322827
Darn, $10. I have some old 2 GB IBM drives with no built-in termination that could use a pass-through terminator like that, but not at a price higher than the drives' worth. :-)
You don't place SCSI terminatation in the "middle" of your device cabling,
ever ...for a compact Mac internal drive cabling, you would have end of the
cable plugged into the logic board, the next plug into the drive, and the
final plug would be the terminator. If you have external drives, you will
still have to have [external] termination at the end of your SCSI chain.
During this discussion, I've been wondering if one might need a terminator at the motherboard end of the cable.
As I understand it, on these old machines the motherboard does not supply any termination. Apple relied on the internal SCSI cable being very short to allow termination of only the internal drive to provide sufficient SCSI termination. So, in fact, only one end of the SCSI chain is terminated, absent external drives.
Could the problem be that with newer drives, the newer drive won't tolerate the unterminated MB end of the cable, even with the very short cable? This argument falls apart, if folks have tried this with a properly terminated external SCSI chain connected and it still didn't work.
So, what I'm thinking is that when one does not have any external SCSI devices connected (with the final one terminated) perhaps one should try plugging a DB25 terminator into the SCSI port on the back of the Mac and see if that solves the problem. Naturally, one would also set termination on the internal drive to 'On'.
Some illustrations:
T: and :T are SCSI termination D is a SCSI device T:D and D:T are a device with termination installed or activated. MB is the motherboard ----- is internal SCSI cabling ===== is external SCSI cabling.
Original Mac config. with no external chain:
T:D----MB Only one end termination, but short cable.
Brandon's suggestion:
T:---D---MB Not relying on drive termination, still only one end term.
Original Mac configuration with external chain:
T:D---MB====D:T Both ends terminated
My proposal:
T:D---MB:T Both ends terminated.
If the internal drives under discussion truly have faulty on-board termination, then this wouldn't help. But if the problem is that the MB end of the SCSI chain is left flapping in the breeze, then a DB25 terminator on the outside of the Mac would solve the problem. And it has the advantage that you must remove it if you install an external SCSI cable, so there's no danger of leaving SCSI termination in the middle of the SCSI cable.
I find this scheme useful with the NuBus Jackhammer card because it has actual termination resistors on the card. It's a pain to open the machine to move the resistors if one is often removing and installing an external segment to the SCSI chain, so I just leave a 68 pin terminator on the external port of the JackHammer and remove it when I install an external device.
Jeff Walther
Jeff Walther
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