Ahh yes!! The trails and tribulations of typing in programs from magazines!! That bit of trivia sure brings back memories for me!! I had to go through the same thing on the Commodore 64 and the same thing happened!! Most of the time to distinguish between 0 and o is that the zero had a slash going right through it, so people wouldn't get confused. Programs started having checksums built in, which had a pre-determined total. If it didn't match, it would say so, and so it goes, LISTing the data statements to find the error!! Very frustrating and time consuming!!! I felt the same way like you did!!