Focal-11

This document serves as a preliminary guide for FOCAL-11, a programming language for the PDP-11/23 computer. It is structured to help users understand the syntax and operational characteristics of the language, noting its similarities to and differences from FOCAL-8. The content covers core aspects of the language, including input/output procedures, control statements (such as DO, GOTO, IF, and RETURN), calculation capabilities, and editing commands. It also includes sections on specific functions (trigonometric, device control, and system functions), operational instructions, and error diagnostics. Appendices provide further technical details, including a list of differences from FOCAL-8, hardware-specific notes, and examples of expansion functions.