terminated

It is very possible to connect another internal hard disk in any
macintosh if you can find the space to put it. I have a IIsi that came
with a Quantum 80 meg drive. When I ran into space problems, I slapped in
another 40 meg quantum that I had sitting on a shelf. Here is what I did.
 
First off, I was concerned about space. Since both drives are Quantum
quarter height drives, I finally decided that the logical place for them
was stacked one upon the other. Fine, they fit snugly. (I have not had a
problem with heat yet, and these drives have been running together for
over two months.

The next problem was connecting the drive. If you have a spare internal
hard disk power cable as I did, then half of your troubles are over. just
splice in the extra cable so that you get one square motherboard
connector and two hard disk power connectors. If you don't have a spare
cable, you will have to buy the wires and connectors which can be found
in any good electronics store for about $10. I would suggest properly
soldering/heatshrinking the connections to reduce the possibility of
shorts or bad connections.

Next, you need a ribbon cable connection. Again, I had a spare hard disk
ribbon cable, and I wanted to be careful in case this didn't word so what
I did was purchase a crimp on 50 pin cable connector that gave me another
male connector in the middle of my spare cable. The part cost $10 again,
and is easily attached with any good wood vice. The theory behind using a
crimp on connector is that if this doesn't work, my original cable is not
damaged, and I can go back to the original setup.

Having done all that, I couldn't be bothered to check the dev notes for
power consumption so I plugged it in and it works like a charm to this
day. 

In a mac II, everything should work the same. Be careful with the ID's of
the drive, and ensure that the terminating resistors on both drives are
intact. I did not try this without the terminating resistors but it
seemed logical that if I am splitting the SCSI chain, that the signal
should be terminated at all the ends.

Let me know if you have any more questions.