VK100 Technical Manual

This document is a Technical Manual for the VK100 (also known as GIGI - General Imaging Generator and Interpreter) interactive graphics terminal, published by Digital Equipment Corporation (DEC) in April 1982.

The manual provides comprehensive information on the VK100 terminal, covering its:

1. Introduction and General Description:

   • The VK100 is a terminal subsystem designed for use with a user-supplied monitor (black and white or RGB color).
   • It operates in both on-line (connected to a host computer) and off-line modes.
   • It features a local microprocessor that supports two interpreters: a ReGIS (Remote Graphics Instruction Set) graphics interpreter and a GIGI BASIC language interpreter, allowing it to execute programs and process graphics commands locally.
   • It can function as both a text terminal and a graphics terminal, acting as a translator between the operator and the host computer. A "locator mode" provides a cross-hair cursor for screen point identification.

2. Installation:

   • Details site considerations (lightweight, fits on desk, requires monitor placement, ventilation).
   • Provides procedures for unpacking, repacking, and physical installation.
   • Explains how to set up the terminal using an eight-position SET-UP switch pack (DIP switches) on the rear, which configures parameters like baud rate, parity, power frequency, and communications interface.
   • Includes specific instructions for connecting to various monitors (Barco Model GD33, typical B&W) and the optional LA34VA Graphics Printer (directly or in a daisy-chain configuration to share the printer among multiple VK100s).

3. Operating Information:

   • Describes the terminal's keyboard controls, including standard keys, special function keys (SET-UP, Arrows, BREAK, HARDCOPY, LOCATOR, TEXT, RESET, DELETE, RETURN, LINE FEED, NO SCROLL, CONTROL, ESCAPE), and their functions in various modes.
   • Outlines the visual (LEDs like ON-LINE, LOCAL, BASIC, HARDCOPY) and audible (keyclick, beep) indicators.
   • Explains the extensive SET-UP Mode, which allows operators to customize over 30 parameters such as transmit/receive speeds, line/local mode, BASIC mode, parity, XON/XOFF flow control, scroll mode, display margins, text/graphics display behavior, and self-test options. These settings can be changed manually via keyboard or by the host computer using escape sequences.

4. Programming Summary:

   • Details keyboard-generated ASCII codes and various control characters supported by the terminal.
   • Explains the use of multiple character sets (UK, US ASCII, and three user-programmable soft character sets).
   • Summarizes the terminal's compatibility with both older VT52 and newer ANSI control sequences.
   • Provides overviews of ReGIS command structure (for graphics) and GIGI BASIC commands and functions.

5. Theory of Operation:

   • Presents a block diagram and detailed functional theory of the terminal's core components: the Terminal Controller Module (CPU, Vector Generator, I/O Ports, Keyboard, Power Supply).
   • Explains the CPU's role (8085 microprocessor, memory addressing, machine cycles), memory refresh, and interrupt handling.
   • Describes the Vector Generator, responsible for drawing characters and vectors, including the mathematical concepts for arbitrary vector drawing (Bresenham algorithm).
   • Details the I/O Port overview (8251A UART for serial data, EIA and 20 mA current loop interfaces) and Hardcopy Overview, explaining how screen images are output to the printer and the logic behind daisy-chaining multiple terminals to one printer.

6. Testing and Troubleshooting:

   • Covers the terminal's self-test programs (power-up and diagnostic tests) and how to invoke them.
   • Explains the error reporting system, distinguishing between fatal errors (terminal rendered useless) and non-fatal errors (terminal remains usable with some limitations), indicated by LEDs and on-screen codes.
   • Provides detailed troubleshooting tables for various symptoms (e.g., no power, video issues, hardcopy problems, communication failures), outlining checks to perform and recommended corrective actions (often involving module replacement, as the VK100 itself is not user-adjustable for most issues, though the monitor often is).

7. Appendices:

   • VK100 Terminal Specifications: Lists detailed physical (dimensions, weight, power) and performance specifications (program memory, display outputs, visual attributes, keyboard, communication types and speeds).
   • Calculations: Provides technical calculations related to vector generation.
   • Illustrated Parts Breakdown (IPB): Contains diagrams and lists of parts for various assemblies within the terminal, primarily for repair and replacement purposes.

In essence, this manual serves as a comprehensive technical guide for setting up, operating, programming, maintaining, and troubleshooting the Digital VK100 graphics terminal, providing an in-depth look at its features, architecture, and repair procedures from the perspective of its 1982 release.