Troubleshooting Guide

Table of contents

Virtual Terminal (VT) emulation troubleshooting checklist

  1. Emulating the VT keyboard in Host On-Demand by remapping the the NumLock key
  2. VT 420 features that are not implemented
  3. VT 420 keyboard limitations
  4. VT 420 character set limitations

Emulating the VT keyboard in Host On-Demand by remapping the the NumLock key

The NumLock key toggles NumLock function states when remapped. The circumvention for this is to map both the NumLock on and NumLock off keys to the same value, and then map the scrolling key values to an ALT+key sequence. You can use the Host On-Demand Administration client or the Deployment Wizard to remap the keys.

For example, using these predefined Host Functions,

  1. Map the keypad with Numlock on:
  2. Map the keypad with Numlock off:
    Note: When you remap the following keys, a pop-up box appears. Click OK, and an additional entry appears in the table in the keyboard remap screen for the key.
  3. Remap Editing Functions to Alt Sequences (make sure Numlock is off)

VT 420 features that are not implemented

The following VT 420 features are not implemented:

VT 420 keyboard limitations

Some local function keys cannot be enabled or disabled in Host On-Demand VT sessions, and menu keys that are mapped to menu commands are not available as local function keys. For example:

The following VT modifier keys are not visible to Host On-Demand VT sessions:

The DECEKBD report is not supported due to technical limitations regarding the determination of the state of the keys on the keyboard.

Due to limitations in Java keyboard handling, Host On-Demand does not map by default the numeric keypad keys so that they can differentiate between numeric mode and application mode.

VT 420 character set limitations

All characters in the terminal screen must be stored as Unicode values. The following character sets contain characters that can not be matched to a Unicode value:

Character SetPosition
Dec Technical Character set2B, 2C, 2D, 2E, 2F, 30, 31, 32
PC Multilingual/International - Left Side08, 17
PC Multilingual - Right Side9B
PC SpanishA9, AA
PC Danish/Norwegian9B

Host On-Demand does not support the use of Raster fonts for VT emulation. VT emulation is dependent on the Java Virtual Machine's available set of fonts for rendering the VT terminal screen. Each operating system and browser combination is missing some of the characters contained in a few of the new character sets. The number of non-renderable characters and their positions varies by operating system and browser, so they are not listed here.

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