Two windows in the buffer
- Program history, with most recent information at the top and
oldest at the bottom.
- Evaluation area showing current expression and the values
of "current" variables. New expressions can be evaluated,
but you shouldn't "alter the state" of the computation.
- Useful commands: C-N, C-P go up and down the
history; p allows the computation to continue in many cases;
e shows more details of the values of variables.