VT420 Video Terminal Programmer Reference Manual Update

This document serves as an update to the VT420 Programmer Reference Manual, specifically detailing how to integrate French Canadian, Greek, Hebrew, and Turkish keyboards and character sets with the VT420 terminal. It provides information for both the VT420 worldwide model and the model with PC TERM mode.

The update covers several key areas:

• VT420 Features: Introduces new features, explains how to select various keyboard dialects (French/Canadian, Greek/N-A, Hebrew/N-A, Turkish-F, Turkish-Q), and guides on choosing appropriate 8-bit and PC character sets from the User-Preferred Supplemental Set (UPSS).
• Character Encoding: Describes additional Greek, Hebrew, and Turkish character sets, including DEC Supplemental, ISO Latin, CRM, and 7-bit National Replacement Character Sets (NRCs), along with French/Canadian character sets.
• Keyboard Codes: Illustrates new keyboard layouts for Greek, Hebrew, and Turkish ANSI and PC keyboards, and outlines the functions of their unique special-function keys.
• Control Functions: Details the control functions used to designate character sets via SCS sequences and assign User-Preferred Supplemental Sets (DECAUPSS). It also explains control functions received from the host for emulating VT series terminals (VT100, VT400 modes) with Greek, Hebrew, and Turkish functionality, including the Hebrew Encoding Mode (DECHEM).
• Cursor Management: Explains additional control functions for cursor movement and provides a correction regarding the Page Cursor-Coupling Mode (DECPCCM).
• User-Defined Keys (DECUDK): This section replaces the original DECUDK information, describing how to program user-defined keys for VT420 models without PC TERM mode, including memory space management and loading guidelines. It also covers UDKs for PC TERM mode keyboards, with expanded memory space for user-defined keys.
• VT420 Reports: Lists additional reports the VT420 terminal sends to the host system, such as Keyboard Device Status Report (DSR), Terminal State Reports, Presentation State Reports, and Mode Settings, to support the new keyboard dialects and features.
• PC Emulation: Describes the additional PC keyboards and character sets (French/Canadian, Greek, Hebrew, Turkish) available in PC TERM mode and the procedures for enabling or disabling this mode.

The document's primary purpose is to extend the existing programmer's reference with comprehensive details on internationalization capabilities, ensuring developers can effectively implement support for these languages on the VT420 terminal.