Focal-11

This manual provides comprehensive documentation for FOCAL-11, an easily learned high-level programming language designed for the PDP-11 computer. It covers the philosophy, program structure, and command set of FOCAL-11. The manual includes detailed chapters on:

• FOCAL-11 Arithmetic: Explains number formats and variable naming.
• Commands: Covers input/output (TYPE, ASK, OPERATE, KILL), computational (SET), control (GO, IF, DO, RETURN, QUIT, FOR, XECUTE), and editing commands.
• Functions: Details trigonometric, logarithmic, and hardware-specific functions (UNIBUS, A/D, Clock, Graphics for VT-11 and VT55).
• Implementation: Provides notes on debugging, creating off-line programs, and estimating program length for both paper tape and RT-11 versions.
• Advanced FOCAL-11: Discusses data formats, adding user-defined functions (FNEW), and asynchronous I/O.
• RT-11 File Capabilities: Describes library operations for file management and virtual files.

The manual also includes extensive appendices detailing error diagnostics, command summaries, and instructions for generating FOCAL system configurations.