Row reset now working.

Turns out that clocking the reset pulse to the -5.5V (asserted) level was causing enough loading on the VrstOff line to reset all of the unaddressed rows, effectively applying a global reset.  Dropping the reset clock (prstOn) to -2V/-4.5V does not eliminate the loading, but reduces it to the point where the reset is only applied to the intended row pair.

We're clocking nominally now.  The image at left was taken at ctdelay = 5, which give almost 4Hz frame rate.  It's a difference between two slices of a SUTR 8-1-4-4 file.  The fluorescent bulb in the ceiling light is saturating so it comes out dark in the difference.

There are still some clocking issues to deal with.  We are not presently sampling the reference pixels as we want to, and I need to make up some short-scanning clock tables, but these are pretty simple adjustments.

At this stage I think we're ready to install the SB375 mux in EXES and image the 'string of pearls'.