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

To: Clarence Dodge who wrote (9221)	11/10/1999 6:27:00 PM
From: QwikSand	Read Replies (1) \| Respond to of 14778

You should be able to use both the 68-pin and 50-pin onboard SCSI connectors. You have to terminate the other ends of both chains. On some current motherboards there are actually three SCSI connectors: a 50-pin for slower narrow devices, a 68-pin for single-ended Ultra SCSI, and another 68-pin for LVD (low-voltage differential) Ultra2-SCI. In one of my machines I am using all three of them at the same time: an Ultra HD on one 68-pin connector, 2 Ultra2 HD's on the second 68-pin connector, and a Fast SCSI CDROM drive plus a Fast SCSI HD on the 50-pin connector. All internal. It works fine now. However, I discovered I had problems using certain 50-pin devices such as tape drives and CD burners in this setup, and had to move them to another SCSI adapter. It's weird, and is no doubt an Adaptec silicon bug or a motherboard bug somewhere. Regards, --QwikSand

To: Clarence Dodge who wrote (9221)	11/12/1999 2:57:00 AM
From: Zeuspaul	Respond to of 14778

You answered all of my questions. With the help of QwikSand and others it looks like you have a good handle on your SCSI setup. I do not think you will have to change any termination on the motherboard host adapter. Since it is working now and you are using both SCSI chains (not really sure if you have one SCSI chain or two but who cares if it is working?) 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? In your new setup you will have to remove the termination on the CD and enable the termination on the Jaz..just reiterating what has already been said. Sometimes..and I do not remember the details..the SCSI host adapter has an 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. That is where I am a bit confused on the termination. 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. Anyhow I think it is academic as said above no need to change the mobo SCSI termination if it is working now. Zeuspaul

To: Clarence Dodge who wrote (9221)	11/12/1999 3:02:00 AM
From: Zeuspaul	Respond to of 14778

The connector you found is the same as what I use...except in my case the connector is already attached to the internal ribbon cable. You will probably have to buy a new internal ribbon cable. I do not believe the one you have is long enough. Also, most standard internal ribbon cables may not work. The plug for the CDROM needs to be about in the middle of the cable...leaving room for the rest of the cable to go to the case fitting. Zeuspaul

To: Clarence Dodge who wrote (9221)	11/12/1999 3:19:00 AM
From: Zeuspaul	Read Replies (3) \| Respond to of 14778

There may be another option. 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. I do not know if this would effect performance. 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. Then you could go directly to the in/out connector with a shorter internal ribbon cable. This may..not sure here either..allow you to disconnect the Jaz drive without having to crack the case and change termination on an internal device. Zeuspaul