UNDO on Prime

[JDW]

I actually clicked "Search" (upper right area of this browser window) and tried to search for this topic, but when click Search I get a blank page in my browser. The page it fails to load is this:

http://www.hpmuseum.org/forum/search.php

I tried it in other browsers on my Mac and I still get a blank page. Anyone else?

Anyway...

There is UNDO on my 28S, 48GX and 50g, printed right there on the calculator where I can see it. But how do I invoke UNDO on the Prime?

And no, ESC is not UNDO.

Here's how UNDO works on my 28S:

1. Push "5" then ENTER.
2. Push "6" then "-", which yields the answer: -1
3. Push the RED button and 8 to UNDO. 5 returns to the stack. Perfect UNDO.

So again, how do I accomplish this kind of UNDO on the PRIME? I'm talking about "UNDO last action."

Thanks.