Speaking of onboard SCSI controllers

[Mike Bilow]

Alex wrote in a message to Mike Bilow:

 A> I've heard that an Adaptec 2940 (the PCI card ;-) ) has three 
 A> connectors (one external, two internal), and only one of the 
 A> internal conncetors can be used at a time.

No.  There are three connectors:

   A.  Internal wide
   B1. Internal narrow
   B2. External wide

You can use:

   1. A only            -- termination high on, low on
   2. B1 only           -- termination high on, low on
   3. B2 only           -- termination high on, low on
   4. A and B1          -- termination high on, low off
   5. A and B2          -- termination high off, low off

 A> I've noticed on my generic motherboard, there are two SCSI 
 A> connectors (one narrow, one wide).  As I'm in the market for a 
 A> ZIP drive, I was wondering if I can connect the three internal 
 A> (narrow) devices on one connector with my existing three 
 A> connector cable, and hook up an external device (with the 
 A> little thingy the reseller gave me) to the second connector (at 
 A> the same time).

In the AHA-2940 card, the B1 and B2 connectors are essentially the same, and
you can use only of the two at a time.  In your motherboard, both of the B1 and
B2 connectors are probably represented by the single narrow connector.  You can
probably therefore use both motherboard connectors at the same time, as long as
you set termination on the motherboard to high on, low off.

 A> Secondly, I was curious how one would assign devices to the 
 A> upper SCSI ids (>7), since the 7880 seems to support ids up to 
 A> about 14 or so.  The drives I've looked at (external CDs, and a 
 A> few narrow internal HDDs) a few years *grin* back only seemed 
 A> to go from 0 to 6 or 7.

Narrow devices only support PUNs (IDs) 0 through 7.
 
-- Mike