Patch

This document serves as the user manual for the PATCH program, which is designed for use with the PDP-12B computer. The primary function of the PATCH program is to allow users to make small modifications to LINCtape binaries by editing specific locations within a tape block (TBLK) on tape unit 1.

Key details from the manual include:

• Operating Prerequisites: The program requires a minimum configuration of a PDP-12B. It uses specific memory locations (MBLKs 0, 2, and 3 of segment 2, and MBLK 4 of segment 3) with a starting address of 4020.
• Loading: The program is a "load and go" utility initiated by the command LO PATCH, UNIT. The target tape must be mounted on unit 1.
• Usage: The program operates through a dialogue process using the QANDA convention. It prompts the user through four sequential messages (TBLK selection, location selection, value modification, and a final "DO" command to write changes or perform further edits).
• Safety: Raising Sense Switch 0 aborts the operation and returns the user to the DIAL operating system; users are cautioned to ensure this switch is down before loading.
• Technical Appendices: The latter half of the document provides the full source code and a symbol table for the program, detailing the subroutines and logic used for keyboard input, data processing, and tape I/O.