Apple II+ Flakey Inverse Characters

[wrodiger <wrodiger@gmail.com>]

I am resurrecting my old Apple II+ with the hope of installing some
modern solid state disk hardware (CFFA or iDisk). The keyboard is
still a little flakey, but I hope usage will clear that up.

My problem is that inverse characters flicker and contain some random
bits. I have read that there is a XOR operation that is performed on
the character set to create the inverse chars, and I am hoping this
can be as simple as reseating/replacing a couple logic chips to
resolve this. Does anyone know where this logic is? Or is this done in
ROM/software?

Thanks in advance for any help,

Will