Introduction to U/W-FOCAL

This document provides a detailed guide to U/W-FOCAL, an advanced stack-processing language for the PDP/8 system. It covers essential topics including hardware requirements, program loading and startup, control keys, direct and indirect command modes, line numbering, variable naming, and symbol table management. The manual also details arithmetic operators, input/output operations, loop construction, and the use of the trace feature for debugging. Additionally, it explores advanced topics like Program Defined Functions (PDFs) and machine-level programming with FPAL, and includes appendices with patches, character codes, and error diagnostics.