This is the most helpful information I have received yet. Thank you.
I can get to where I am looking at the two drives in Windows Explorer but, when I do, DCIM does not appear anywhere on either of them. I have just been closing the pop-up window that comes up when I hook the phone up to the computer - maybe that's why. I will try it again, this time making a selection in that window as you have suggested. Maybe then the DCIM directory will appear.
Yes, try not closing the pop-up window, you might accidentally be accessing a different drive.
I gather that, in order to copy pics from computer to phone, I have to create a new directory ("Pictures") to receive them whereas, in copying pics from phone to computer, I copy them out of the DCIM folder on the phone and do not have to create any new folder - is that right?
Yes, that is correct. We just have to find your DCIM folder