FOCAL-GT RT UsersMan

This document is the user's manual for FOCAL-GT/RT, a specialized version of the FOCAL-11 programming language developed by Digital Equipment Corporation in 1973 for the GT40 graphics system.

The manual outlines two primary versions:

1. FOCAL-GT: This version extends FOCAL-11 with functions to handle the GT40 graphics system and communicate with a host computer. Key features include:

   • Graphical Capabilities: Drawing lines (FVEC), moving the display beam (FMOV), plotting absolute points (FPT, FSET), and inserting italic characters (FTXT).
   • Display Control: Setting various graphic modes like line type, intensity, blinking, and light pen sensitivity (FDIS).
   • Light Pen Interaction: Functions to sense light pen hits (FLP) and retrieve coordinates (FXCO, FYCO).
   • Display Management: Manipulating the display file, clearing graphics (FCLR), and adjusting file sizes (FSKP).
   • Terminal Emulation: Functioning as a terminal to a host computer, displaying I/O, saving/restoring FOCAL programs, and executing programmed monitor commands.

2. FOCAL-RT: This version includes all the functionalities of FOCAL-GT and adds specific functions for the Laboratory Peripheral System (LPS), enabling real-time data interaction:

   • LED Display Control: Loading integer values to the LPS numeric display (FLED).
   • Timer Functions: Setting and reading a 16-bit timer for precise timing in FOCAL operations (FTIC).
   • Analog-to-Digital Sampling: Sampling data from A/D channels, with options for single, dual, or Schmitt-triggered sampling into a buffer (FSAM).

The manual also covers essential system operations like assembling, loading, restarting, and extending FOCAL-GT/RT with new functions, and provides appendices with error diagnostics, command summaries, and technical details of the display file structure. It is intended for users already familiar with FOCAL programming and the GT40 graphics system.