To operate the history feature:
 Press ^Z
 Press the number key corisponding to the index of the item of your choosing.

Note: if you enter the same command more than once, it will not be added to the
history multiple times. It will of course be re-added once it has passed out of
the history. This economizes on use of history space (so you do not waste it on
ten copies of 'ls' and also you can rapidly reenter commands without reading the
list.)

Currently it has that buffer problem with stdin described in our email.
I'm working on fixing it before it's due saturday (night?).