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Pastimes : Dream Machine ( Build your own PC ) -- Ignore unavailable to you. Want to Upgrade?

To: Zeuspaul who wrote (9255)	11/12/1999 10:17:00 PM
From: Clarence Dodge	Read Replies (1) \| Respond to of 14778

ZeusPaul LONG POST Warning In your current setup the harddrive is terminated at the end of it's chain and the CD is terminated at the end of its chain? I believe I have two Scsi chains. One coming off the 50 pin mobo connector to the terminated 50 pin Plextor CD-R. The other coming off the 68 pin mobo connector to the SCSI hardrive. Whether or not the scsi hardrive is terminated or not is a can of worms I've been wrestling with ever since I got the drive. The drive does not have a termination jumper (TE) designation. It does have a termination power (TP) jumper and an (SE) jumper which enables auto switch between Single Ended or LVD operation. Quantum support tells me the drive does indeed NOT provide termination. I wish I had figured all this out before purchase, 'live and learn' is in full play on this one. Quantum says use a end-of-ribbon type terminator, they even specified one from SCSIPRO. No problem, right. Well, when I have the SCSI Pro terminator at the end of the 68 pin chain NT will not finish booting. When the terminator is not present everything is fine. I've spoken at lenght with tech supervisors at both Quantum and SCSIPRO without success. Basically Quantum ended with the statement that some devices will operate without termination. SCsiPRO says at some point I could experience data loss etc. but they have not been able to get their terminator to work on my system. So thats the situation with my 68 pin chain. Your option to combine the cd-r on that chain is very interesting as I may be able to provide termination with it. Once again I say 'Why didn't I think of that'. Maybe that could be my new nick <g> extra chip in it between the 50 and 68 pin setups. The purpose is to act as some kind of isolator enabling you to use both the 68 and 50 pin connectors at the same time...as you are currently doing. Albeit with the 68 pin chain termination anomaly... I do not know if you have one SCSI chain or two SCSI chains. I think you have one...otherwise it is called a dual channel SCSI host adapter and I think you have a single channel host adapter. Somehow the answer to the above problem is involved here... You will probably have to buy a new internal ribbon cable. I do not believe the one you have is long enough. Looping around to the CD and back down to the mobo approaches 5'. QwikSands other option to disable termination on the mobo and go up to the terminated CD is 2' shorter so I prefer this route. Your idea to put the CD on the 68 pin chain would not require me to purchase any additional interior ribbon. That's two good reasons to try it. I recall seeing an adapter in your cable link that addressed termination issues with mixed pin configurations. If you go from 68 to 50 pins the 'missing' 18 pins have to be terminated. I believe the 18 pins (or fraction thereof) are terminated at the adapter and the rest would be terminated (in your case) at the CDROM. Yes SCSI seems quite finicky. A tricky adapter may not be welcomed. I'll take a look at this adapter. Mixing SCSI speeds on the same chain is sometimes not recommended. I do not know enough about it to say one way or the other. I agree it sounds non-kosher. But if it worked I would be solving that long standing termination issue. That would be a real kewl thing. All in all..i feel like giving your approach a try since it does not require any purchases I would need to return if things did not work out. Clarence

To: Zeuspaul who wrote (9255)	11/12/1999 10:39:00 PM
From: Clarence Dodge	Read Replies (1) \| Respond to of 14778

EDIT it does not require any purchases I would need to return if things did not work out. oopps.. forgot about that 68 to 50 pin adapter..

To: Zeuspaul who wrote (9255)	12/8/1999 9:59:00 PM
From: Clarence Dodge	Read Replies (1) \| Respond to of 14778

You could put the CDROM on the same chain as the harddrive. I recall seeing an adapter in your cable link that addressed termination issues with mixed pin configurations. If you go from 68 to 50 pins the 'missing' 18 pins have to be terminated. I believe the 18 pins (or fraction thereof) are terminated at the adapter and the rest would be terminated (in your case) at the CDROM. In this case you would remove termination from the harddrive and leave termination enabled on the CDROM. Then you could go directly to the in/out connector with a shorter internal ribbon cable. Well I finally got around to collecting the parts to implement the above. I thought it was the neatest alternative that was presented to add an ext Jaz to my scsi chain. And it gave me an opportunity to resolve the termination issue on my 68 pin ribbon by using the actively terminated 68 to 50 pin adapter plus enabling termination on the 50 pin device. This is on the last connector of the ribbon. So, theoretically, at least, the 68 pin ribbon is properly terminated now. All/both devices on the 68 pin ribbon are working ok, strangly enough with the host adapter termination either enabled or disabled. I also found some new documentation on the Aopen site presenting this setup. BUT the simpler run off the 50 pin mobo connection to the int/ext adapter and on to the terminated Jaz is not ok. Both enabled and disabled host adapter termination options end in a BSOD during bootup when the Jaz is connected. Disconnect the Jaz and all is ok. This whole exercise has been worth alot in terms of getting down and dirty with scsi chains. I've learned much. But at this point, I think I'm ready to take Howards original advice and just get an adapter board to service the ext Jaz. I will be defeated for the first time by a hardware issue but the education has made it worth my time and the few bucks extra I spent. BTW Do you or anyone else know of any scsi diagnostic sw which would tell me what is actually going on in terms of termination and whatnot on a scsi chain. I appear to be blindly following the rules of scsi as I learn them, and hoping for success determined merely by whether or not a device works. Sems there should be a way to 'see' what is going on in the chain. Does Adaptec's EZ-SCSI do this? Clarence