single tone during 41cx program execution, error?

[twdeckard]

Greetings,

I have a short program which is doing some elaborate parsing of an alpha extended memory file and I am getting a single tone repeatedly intermittently during one of the loops.

Before I transcribe the FOCAL, can anyone deduce an explanation? Is this an error signal? Program execution does not halt.

Interestingly subsequent/random executions of the program run off the end of the file and require me to ED it and move the file pointer to the beginning, so likely I am doing something very wrong.

Thanks!