6
Typing Additional Characters

The VT420 lets you type more characters than appear on your LK401 keyboard. For example, you can type accented characters or a © symbol. This chapter lists the available characters and shows you how to select them.

To enter one of these characters, you type a sequence of keys. Most sequences begin with one of the Compose Character keys. If you use the German keyboard, you use the Group Shift key instead of Compose Character.

This chapter describes the following types of key sequences:

• Three-stroke Compose Character sequences (with all LK401 keyboards)
• Group Shift sequences (with the German keyboard)
• Two-stroke key sequences (with keyboards that have nonspacing diacritical keys)
• Hexadecimal key sequences (for programmers)

Two basic factors determine the key sequences you can use.

• The keyboard dialect setting, which should match your keyboard model (Chapter 3)
• The character set the terminal is currently using (Chapter 5)

What Characters Can I Type?

You can type any of the characters in the character set the terminal is currently using. You can select from two multinational sets (DEC Multinational character set or ISO Latin Alphabet No. 1) or many national replacement character sets (NRCs). By default, the VT420 uses the DEC Multinational character set. Chapter 1 describes multinational and national character sets, and Chapter 9 shows each character set.

The character set mode feature in the General Set-Up screen sets the terminal to work with 8-bit multinational or 7-bit NRC sets.

Key Sequences with Nonspacing Diacritical Keys

Table 6-1 lists the keyboards that have keys with diacritical marks. Table 6-2 lists all the additional characters for all character sets in the VT420 terminal. Many of these characters include a diacritical mark. For example, À includes an acute accent.

To enter a character that has a diacritical mark, you press the diacritical key followed by the character. If your keyboard does not have the diacritical key, you must press the Compose Character key followed by the correct key sequence listed in Table 6-2.

To use diacritical keys, you must be using a multinational character set.

How to Type a Character Using the Compose Character Key

To enter a Compose Character key sequence:

1. Find the character you want to type in Table 6-2.
2. Press the Compose Character key. Compose appears on the keyboard indicator line, indicating the terminal is in the compose mode.

   NOTE: If the Compose Character key does not work, check the setting of the compose key feature in the Keyboard Set-Up screen (Chapter 5).

3. Type the sequence in Table 6-2 for the character you want.

Example

To type an é:

1. Find the é character in Table 6-2.
2. Press Compose Character.
3. Type e and ' (apostrophe).

NOTE: If you try to enter a character that is not available in the current character set, a warning bell sounds. See "Invalid Sequences" in this chapter.

How to Type a Character Using the Group Shift Key

If you select the German Keyboard dialect in the Set-Up Directory screen, the Group Shift replaces the Compose Character key.

Many keys on the German keyboard have a second group of legends on the right half of their keycap. These legends are called Group-2.

To enter a single character from Group-2:

1. Press and release the Group Shift key. Group Shift appears on the keyboard indicator line at the bottom of the screen. This indicates that you have selected the Group-2 keys.
2. Type the key that has the desired character on the right half of the keycap. The character appears on the screen, and the Group Shift indicator turns off.

Example

To type an ø:

1. Press Group Shift.
2. Type the key that has the ø character on the right half of the keycap: O ø.

To enter a series of characters from Group-2:

1. Hold down the Group Shift key. Group Shift appears on the keyboard indicator line at the bottom of the screen. This indicates that you have selected the Group-2 keys.
2. Type the series of keys that have the desired characters on the right half of their keycaps. The characters appear on the screen.
3. When you are done typing characters from Group-2, release the Group Shift key. The Group Shift indicator turns off.

Invalid Sequences

When you complete a valid compose of group-shift sequence, the character appears on the screen and the Compose or Group Shift indicator at the bottom of the screen turns off. If you use an invalid sequence, the VT420 cancels the sequence and sounds the warning bell.

Some compose characters require that you type the key sequence in the order listed in Table 6-2. If you do not follow the order, the sequence is invalid and the warning bell sounds. If the terminal does not display the character, repeat the sequence exactly as shown in Table 6-2.

NOTE: Pressing a function key cancels a compose or group-shift sequence without sounding the bell.

You can turn the warning bell on or off in the Keyboard Set-Up screen (Chapter 5).

Canceling or Restarting a Key Sequence

If you accidentally start a key sequence by pressing Compose Character, Group Shift, or a nonspacing diacritical key, press the <×] key. This immediately cancels the sequence.

If you press Compose Character during a compose sequence, a new three-stroke sequence starts from that point. The first sequence is canceled.

If you press any of the following keys during a key sequence, they cancel the sequence and perform their usual function:

• Tab
• Enter
• Any top-row key
• Any Ctrlother key combination

Hexadecimal Key Sequences

This feature is primarily for programmers who are familiar with character coding and hexadecimal representation.

The VT420 uses coded character sets to exchange data with a host computer. The code for a character can be represented by a pair of hexadecimal digits. With the VT420, you can enter any 8-bit code by pressing Compose Character or Group Shift followed by two hexadecimal digits typed on the numeric keypad.

When you press Compose Character or Group Shift, the terminal assigns hexadecimal values to the numeric keypad keys (Figure 6-1). The character set tables in Chapter 9 show you the hexadecimal values for each character in the standard character sets.

NOTE: The character set mode and UPSS features in the General Set-Up screen do not affect hexadecimal compose sequences.

Examples

• You can use a hexadecimal compose sequence to send the US (unit separator) control character. The hexadecimal value for US is 1F. Figure 6-1 shows the numeric keypad.
  1. Press Compose Character or Group Shift.
  2. Press 1 on the numeric keypad.
  3. Press , on the numeric keypad.
• You can use a hexadecimal compose sequence to send the DCS (device control string) character. The hexadecimal value for DCS is 90. Figure 6-1 shows the numeric keypad.
  1. Press Compose Character or Group Shift.
  2. Press 9 on the numeric keypad.
  3. Press 0 on the numeric keypad.

NOTE: If the terminal mode feature in the General Set-Up screen is set to VT400 Mode, 7 Bit Controls, the 7-bit representation of DCS (ESC P) will be sent.

Invalid Hexadecimal Sequences

If you enter an invalid sequence, the VT420 cancels the sequence and sounds the warning bell. You can turn the warning bell on or off in the Keyboard Set-Up screen (Chapter 5).

Figure 6-1 Hexadecimal Compose Keys