VT50 Video Terminal Programmer's Manual

This document serves as a comprehensive programming guide for the VT50 Video Terminal. It is structured to assist both novice and experienced users, starting with fundamental operational instructions and then delving into advanced programming aspects.

The manual covers:

• Basic Operation: Instructions on powering up, understanding cursor movement, displaying and scrolling text, and changing screen content. It details how the keyboard directly controls the cursor in Local mode and how these commands relate to ASCII and Escape Sequences.
• Terminal Architecture: An overview of the VT50's internal structure, including data transmission and reception, memory organization (main for display, secondary for housekeeping), and how the cursor relates to memory addressing.
• Character Processing: Explains how the terminal handles ASCII characters, distinguishing between displayable characters and control codes, and outlines the conversion of lowercase to uppercase for display.
• Commands and Escape Sequences: A detailed list of 7-bit ASCII control codes and specialized Escape Sequences recognized by the VT50 for functions such as ringing the buzzer, cursor manipulation (backspace, tab, line feed, home), screen/line erasure, terminal identification, and controlling screen display modes (Hold Screen, Auto Print).
• Interfacing with a Computer: Describes Local and Remote operational modes, Full Duplex settings (with or without local copy), and the interaction between the keyboard, terminal, and host computer.
• Communication Protocols: Information on selecting communication rates (baud rates from 75 to 9600) via rotary switches, the use of even parity for data transmission, and the function of the BREAK key for interrupting data flow or reinitializing the terminal.
• Optional Copier: Details the operation of the optional hard copy copier, including screen-by-screen and continuous auto-print modes, keyboard controls, and corresponding Escape Sequences for host computer invocation. It also addresses the copier's slower print speed relative to screen display, necessitating data buffering and XOFF/XON flow control.
• Specifications and Troubleshooting: Provides technical specifications for the VT50 (dimensions, weight, display format, keyboard, terminal modes, communication) and a basic troubleshooting guide for common copier problems.