Local (predictive?) echoing (was: Is Intel exceptionally unsuccessful as an architecture designer?)

The way I implemented it was by updating the "official" back frame buffer,
and compare the update with the visible front buffer. If at any time a write
to the back buffer did not result in something that was already in the front
buffer, I just copied the back buffer to the front and went on from there.

The only application I use which is still doing something like it
nowadays is `mosh`, and I must say that it is a great feature.
[ It's occasionally "problematic", such as when I type a password before
  the prompt appears, so `mosh` doesn't know yet that it shouldn't be
  displayed.  🙂 ]


        Stefan