The HP-33E/C that could have been.

[Kostas Kritsilas]

Its not a 2:1 difference in all instances. The 2nd and INV keys on the TIs were generally NOT separate keystrokes, or program steps, if you want to think of it that way. There is not doubt that the equivalent programs used fewer program steps (on HPs with merged program steps), but the relationship is a lot more complex than assuming a straight 2:1 or 3:1 relationship; it is very dependent on what the program actually did, and how it was programmed.