Introduction to U/W-Focal for the PDP/8

This document provides a comprehensive guide to U/W-FOCAL (UWF), an advanced, interactive, stack-processing language designed for the PDP/8 computer. UWF is described as a more powerful, easier-to-use version of the original FOCAL language, combining features similar to BASIC and FORTRAN with built-in editing capabilities.

Key areas covered in the manual include:

• System Setup: Instructions for hardware requirements, loading the binary tape, and initial program configuration using the switch register.
• Command Basics: Explanations of direct and indirect commands, line numbering conventions, and how to use the built-in editor to modify, move, or erase program lines.
• Programming Concepts: Detailed rules for arithmetic operators, punctuation, variable naming, and the use of the symbol table. It also covers "protected" and "secret" variables.
• Input/Output: A deep dive into the ASK and TYPE commands, including special formatting operators (!, ", #, $, %, :) used to control terminal output and input.
• Control Flow: Descriptions of branching and loop commands, including GOTO, DO (for subroutines), IF, ON, JUMP, LINK, QUIT, and looping structures (FOR, NEXT, BREAK).
• Functions: A library of built-in transcendental (log, exp, sine, etc.), numerical, and character-manipulation functions. It also provides a framework for creating user-defined functions (PDFs).
• Advanced Features: Information on utilizing extended memory for large data arrays (FBUF, FCOM), parallel I/O module programming (KONTROL, FDIN), and machine-language interfacing via FPAL.
• Maintenance: An appendix of patches for custom configurations, a summary of all commands and functions, and a list of error codes for troubleshooting.