8K Focal Display

This document serves as the program library documentation and user manual for the "8K FOCAL DISPLAY" software, an overlay for the 8K FOCAL programming language designed for use with the PDP-8/i computer, KV8/i display controller, and VT01 storage tube.

Key Features:

• Plotting Capabilities: Provides expanded vector-plotting (relative, absolute, circles, and arcs) and character display functions.
• New Functions: Introduces two primary functions: FX for vector/arc plotting and cursor readout, and FDIS to control character display and switch between "scope mode" and "teletype mode."
• Interactive Controls: Includes joystick support for interactive programming and an "interrupt-bar" that allows users to trigger program routines (via a "DO 31" command) while the program is running.
• Editor: Features a "Keyboard-to-scope" editor that allows users to type text directly onto the screen, with commands (CTRL sequences) to control character size and placement.
• Lazy Plot Routines: An addendum provides a set of routines for quick plotting, enabling users to draw axes, subdivisions, legends, and histograms without complex manual scaling.

Technical Specifications:

• Hardware Required: PDP-8/i, 8K core memory, KV8/i interface, and VT01 storage tube.
• Software Required: FOCAL 69 and the 8K FOCAL overlay.
• Memory Usage: Occupies locations 3140-3377 and 16532-17577.
• Variable Expansion: Offers an option (CTRL/V) to expand the variable storage area from 128 to 201 variables at the expense of other functions.

The document also includes an errata sheet for known bugs, detailed technical breakdowns of the MODE instruction bit structure for controlling vector types, and guidance on saving and loading the program in various system environments.