Focal Library (Linctape Focal for the PDP-12)

This document provides documentation and assembly code for the FOCAL Library system designed for the PDP-12 computer using LINCtape. The system allows users to store up to 62 programs on a single tape and provides an index routine to display, update, and manage the library.

Key features include:

• System Components: The library consists of two main parts: the initial calling routine (FOCALL) and the index routine (FOCINDEX).
• Index Management: Program 00 acts as the system index. Users can display the index, add new programs, or modify existing entries. It includes fail-safe features to recover from crashed indexes.
• Operating Procedures: The document outlines the necessary setup (preparing a second tape by copying the first 50 blocks of the system tape) and instructions for loading and running FOCAL programs. It also provides guidance on how to store preliminary versions of source code for later editing.
• Technical Details: The document includes a core map showing how FOCAL manages memory and details the logic behind loading the FOCAL executive and variable blocks from tape. It concludes with extensive source code listings for the routines involved in the library system.