'Twas brillig, and the slithy toves did gyre and gimble in the wabe

My one will handle upper and lower, but it will only let you type upper. For formatting, it's a script to convert "[]" to "<>", and to prompt for a character whenever it comes across a theta (as that's the only character I'm not likely to use for someting else). It takes a minute or two to transfer from the calculator to the computer, and export the program to a text file using some ancient 16-bit utility. Once I get the script done I'll time it for you :)