I got the user board and the keyboard dongle finished, and the tape board about half done when I ran out of solder.  I don't think in my 20 years of doing electronics have I ever run out of solder, but today it happened. 

Trying the two finished boards - the diagnostic reports those ports as good now!  I did notice one unusual thing - the LED on the user port board blinks at about 2Hz.  That means the VCC line is bouncing up and down on that port.  But not the keyboard power or the tape power.  Those LEDs are constant.  There's something unusual going on -  I guess I'll take a look at the commodore 64 schematic.