In answer to my own question...
free software for Nikon DSLRs. Particularly tethering software:
Nikontrol 3K (which I tied) and
Digicamcontrol (Haven't tried).
After reading lots about no SDK for Nikon D70s and similar Nikons...I was surprised to find Nikonctrol 3K tethered and ran the D70s via USB just fine. Interface is a little clunky but I managed to take a series of snaps with delay and change iso/shutter speed etc. Image came up on control panle, not liveview, but the last image shows.
No magnification of image but, hey it works. Now need to try Digicamcontrol, but, I expect it'll be similar.
Disappointing to see Backyard Nikon touting no support to D70s as no SDK...but hey obviously there is support thru USB!