princ?

So I want to learn LISP.
But I'm stuck at the second assignment in SICP already.
The provided code uses a function called princ but the Scheme IDE, which I downloaded from the MIT website, cannot find it.
What can I do?

>>4
I probably should mention that (read-char) outputs:
[m]READ-CHAR not supported on this port: #[i/o-port 12]