Single-Ended or Wide-Differential?

[Eric House]

Hi,
How do you tell if it is a Single or Wide Differential?
I have seven 1 gig hard drives. I can't seem to get them going on my Mac. I have tried all different jumper settings. Do you think it could be firm wared to work with some speical piece of hardware? Does that have something to do with Single or Wide Differential? I did take them out of some kind of rack. They were on amphibian cards.
Thank You,
Eric

[Patrick Wessel]

Eric,

A simple way to decide if you deal with a single ended or fast wide differential device is the connector. SE uses a 50 pin connector, FWD a 68 pin. But there is no rule without an exception. Unfortunately are there SE devices which use 68 pin connectors...

Are we still talking about the C2247? You are able to identify these guys buy their 'part number' labled on the drive:
C2247-6xx65 - SE
C2247-6xx75 - FWD

[Michael Lampi]

Eric and Patrick,

Both single ended and differential drives can be found with narrow (50 pin) and wide (68 pin) connectors.

The best way to determine which type (SE or Diff) you have is by decoding the drive model number.

Otherwise, you can sometimes determine between the two types by examining the circuit board on the bottom of the drive. High voltage differential (not LVD) drives usually need separate SCSI bus driver chips between the SCSI chip and the bus connector. There are three of these chips on most wide differential SCSI drives. Single ended drives do not have these chips.

Another way to determine if you have disk drives compatible with your SCSI bus is to make sure that their SCSI address does not conflict with any pre-existing devices on your bus, and then connect the drive to the bus. If you can no longer access any devices on that bus then you have just connected an incompatible drive.