I get what you mean and ya thats possible…
This is how I'd do it…
Basically.. you'll want to create a loop where it waits for a keypress
If you press a number you'll tell it to type and add to a string
If you press alpha you'll tell it to switch to letters
If you press 2nd itll have no effect unless you press alpha afterwards..
you'll tell it to stay letters after pressing both until alpha or even 2nd is pressed again…
if you press enter key (105) it will end the loop and then you move on to handle the input
(if you don't press anything you'll have a blank string and it will go on with the rest of your code…)
Above is what u were wanting
After doing that it depends on your program and what you want it for
to determine how you'll handle the input
Anyone feel free to interpret this into ti-basic I'm too lazy to make it
but… if you really need it and you ask nicely I could make it for you..
Show me thanks if I helped =D