POP-1: AN ON-LINE LANGUAGE - R. J. POPPLESTONE

Lisp, etc.) are designed for off-line use. Poi,-1 is for use by a person communicating directly with a computer via a typewriter. With this in mind I have aimed at a tolerable efficiency of execution, and an ability to define and name new operations, with comprehensive monitoring facilities. On the other hand actual error messages are rather simple. At the very lowest level, the computer can be used just as a desk calculator.