That's correct. The silicone cell is so fast, it reads after the lens stops down. That's why you can even use PRE-MC Rokkor lenses on the XD and X-700 cameras in S and P modes -- as long as they have auto-diaphragms.
Minolta could have put a P mode on the XD cameras, and an S mode on the X-700 -- but didn't.
That's correct. The silicone cell is so fast, it reads after the lens stops down. That's why you can even use PRE-MC Rokkor lenses on the XD and X-700 cameras in S and P modes -- as long as they have auto-diaphragms.
Minolta could have put a P mode on the XD cameras, and an S mode on the X-700 -- but didn't.
Before the XD-11 there were the great debate as whether Aperture priority or Shutter priority is better so Minolta idea was to provide the best of both worlds. They didn't think about Program (it took Canon to do it). Then when the X-700 came around it was the P mode that was the big thing so the S mode isn't important any more.
Minolta had already decided on the aperture-priority automatic exposure path with the XE and XK cameras of 1972. Their CDS cells and meter-coupled lenses could easily set the correct shutter speed on an electronic shutter.
By 1977 they figured out how to add shutter-priority exposure with the use of ultra-fast silicone cells.