I have recently purchased an HP 42s and would like to put a "QPI" fraction program on it, specifically, the one kindly put on the web by Mr Erik Ehrling. The other calculator I own is a 48G, but I have never tried programming anything on a calculator before, RPN/RPL or otherwise, so this is a new discovery for me.

I am having difficulty entering in some of these commands and symbols, which I cannot find on the calculator, in the menus.

The ones I am having trouble with are:

Line 49 - the T symbol rotated back 90 degrees (and anywhere in future commands where this symbol is repeated).

Line 95 - XEQ IND ST X (I can only enter XEQ followed by 2 numbers)

Line 103 - RCL ST Y (again, I can only enter RCL followed by 2 numbers, and any future instances where ST follows RCL)

Line 106 - XEQ IND 03 (can't find where the IND comes from, any future instances where IND follows XEQ)

Line 378 - STO ST L (again, unsure where the ST comes from).

Also, if we make a mistake on one of the lines after having entered all nearly 400 lines, how do we correct but not delete a line? The lack of an "edit" or "undo" buttons is something I miss from the 48.

I'm very much looking forward to your responses, thanks in advance.