I think z80man is working on a Prizm IDE.
As of the last time I checked (I don't have a Prizm so I don't stay very up-to-date) you can make Prizm programs in C and assembly on a computer and BASIC programs on-calc.
I'm not sure what the "rule of 3" is, but I might be able to help.
Also, if you're new here, you might want to head over to the Introduce Yourself section and, well, introduce yourself.