GT40/GT42 user's guide

This user's guide provides comprehensive information on the GT40 and GT42 Graphic Display Terminals. It details their operation, including start-up procedures, equipment specifications, programming techniques, and interfacing with other systems.

The GT40/42 is a high-performance graphic display system designed to operate with a PDP-11/10 computer. It can display both alphanumeric and graphic data, excelling in dynamic, fast-changing visualizations such as waveforms. The system can function as a standalone computer or integrate into a larger network. Key components include a Central Processor Unit (CPU), a Display Processor Unit (DPU) with a Bootstrap Read Only Memory (ROM), a Communications Interface Module, memory, keyboard, CRT monitor, light pen, and power supply.

The guide outlines system operation, emphasizing its stable digital and analog techniques for efficient, accurate vector calculation and high-quality image display with features like character generation (upper/lower case, special symbols), hardware blink, and precise resolution. It covers the display processor's instruction set and various data formats. Interfacing is achieved through a parallel Unibus extension for high-speed peripherals and a serial port (DL11 Asynchronous Interface) for host communication. Detailed procedures are provided for initiating the ROM Bootstrap from different system configurations (terminal, paper tape, other devices), including discussions on the Absolute Loader and error handling. Advanced programming techniques such as subroutines, light pen interaction, special characters, and methods for avoiding display flicker and edge violations are also addressed. The document concludes with detailed equipment specifications for all major components and their physical characteristics.