Display Focal

This document provides documentation and assembly code for "Display Focal," a program designed to support the VT01 Storage Display and KV8/I controller on a 4K PDP-8 computer system.

The software provides two primary routines:

• FADC: A routine to clear the display screen.
• FNEW: The main plotting routine, which allows for vector plotting in absolute mode. Users can define coordinates and specify whether vectors are short/long and visible/invisible.

The documentation includes detailed instructions for loading the program into a system using disk or DECtape monitors, as well as instructions for patching the source code if a system device is not available. It also provides a complete assembly language listing of the patch routines and interrupt handlers used to facilitate the display operations.