Cig-8 Mark Ii

Summary: This document serves as the technical documentation and program listing for "CIG-8 Mark II," an overlay for FOCAL 1969 designed to enable interactive computer graphics on non-storage oscilloscopes for the PDP-8 computer.

Key details include:

• Purpose: It provides software simulation of hardware graphics terminal functions, allowing users to assemble and modify display files using FOCAL.
• Requirements: The program requires an 8K PDP-8 with a VC8/I (or equivalent) display interface. Disk/tape monitor and AD08 hardware are optional.
• Functionality: It uses a display file (a vector 1024 units long) to store and manage graphics. It supports various "MODE" functions such as axes, text (horizontal/vertical), lines, and graphs.
• Operation: The document provides detailed instructions for loading, saving, and utilizing the display file, including specific FOCAL commands for creating and manipulating graphical objects. It also includes comprehensive assembly language code listings for the overlay and internal subroutines.
• Limitations: Notable restrictions include the loss of the high-speed reader (HSR) function and specific constraints on FCOM and FDIS storage capacities.