[Coco] Re: Coco Digest, Vol 34, Issue 22

[Tony C]

Message: 4
Date: Sat, 10 Jun 2006 18:46:13 -0500
From: "George's Coco Address" <yahoo at dvdplayersonly.com>
Subject: Re: [Coco] [Color Computer] [coco} IBM SCSI hard disk
       question..

>> Today, I did some research and found there are adapters to convert the 68
>> pin to the older 50 pin connectors. What I've found is that the newer
>> drives will "retro" to the older scheme to accommodate older systems.
>> They
>> are used a lot on older Mac systems and some PC stuff.


Another issue commonly ignore when using  wide SCSI drives (68-pin) on a
narrow (50-pin) cable is that the unused signals on the 68-pin cable that
are not on the 50-pin cable, MUST still be terminated, so as not to float.
If you are lucky, this can be done with a simple jumper on the drive, as
long as that terminator is powered either from the bus, or from the drive.

All of the newer 68-pin drives (80MB?S and faster ) will use low-voltage
differential signalling, which requires special LVD terminators. Care must
be taken when connecting a 68 drive into a 50 pin cable. When an LVD device
is connected to a single-ended bus, the differential sense line should force
the bus into single ended mode.