4
The Keyboard and Indicators

This chapter describes the basic function of each keyboard key and indicator. The chapter also describes two status lines you can display on the screen, the terminal status line and keyboard indicator line. Later chapters provide more information on keys with special functions.

NOTE: A list of common keyboard functions appears at the end of this guide. You can keep a copy of the list near the terminal, as a quick-reference tool.

LK401 Keyboard

The VT420 uses Digital's LK401, keyboard, which comes in many models for use in different countries. Most models are available in a standard or word processing (WPS) version. The only physical difference between all keyboards are the legends on the keys. Appendix D shows the standard versions and the WPS version of the North American/United Kingdom dialect.

The figures in this chapter show the North American/United Kingdom version of the standard LK401 keyboard, unless otherwise noted.

Keyboard Dialect

The VT420 has a keyboard dialect feature that is initially set to the North American Keyboard. If you have a keyboard for a different country or want to use the British dialect, you must change the setting of keyboard dialect feature in the Set-Up Directory screen. Chapter 3 describes how to select the correct keyboard dialect.

Layout

The LK401 keyboard has four groups of keys and two indicator lights. The keys are grouped by function.

• Main keypad
• Editing keypad
• Numeric keypad
• Top-row function keys

The LK410 keyboard also has two audible indicators, a keyclick and bell.

Main Keypad

The layout of the main keypad is similar to a typewriter keyboard, with alphanumeric characters, punctuation marks, and Shift keys. The main keypad also has a number of keys not found on a typewriter, such as the Ctrl modifier key and the Compose Character prefix keys. The German keyboard has a Group Shift key and Alternate Shift key instead of Compose Character keys.

Modifier keys are pressed in combination with another key, to modify the code sent by that key. Prefix keys are pressed and released before pressing another key, to change the function of one or more keystrokes.

Special-Function Keys

The main keypad has the following special-function keys:

Tab	Pressing Tab sends a horizontal tab, which normally moves the cursor to the next tab stop. You can select the tab stops on the Tab Set-Up screen (Chapter 5). Applications can also change tab stops.
Ctrl	Holding down Ctrl and pressing another key sends a control code to the host. For example, Ctrl Z means to hold down Ctrl and press the Z key.
	Pressing the lock key down puts the keyboard in caps lock mode or shift lock mode. You can select the mode from Keyboard Set-Up screen (Chapter 5). The default setting is caps lock mode. In caps lock mode, the alphabetic keys send their uppercase or shifted character when pressed alone. You can use a Shift key to send the shifted character on other keys. You turn caps lock mode on and off by pressing and releasing the lock key. In shift lock mode, all keys on the main keypad send their shifted character. You can turn shift lock mode on by pressing the lock key. You can turn it off by pressing either the lock key or Shift key. When the lock key is down, the lock indicator turns on and the lock symbol (or the word Lock) appears on the keyboard indicator line.
Shift (left and right)	Holding down Shift and pressing a standard key sends the shifted (top) character on the key. Holding down Shift and pressing a special-function key starts a predefined control function. For example, Shift F2 (Print) means to hold down Shift while pressing the F2 (Print) key.
Return	Pressing Return sends either a carriage return or a carriage return and a line feed (selected in the General Set-Up screen, Chapter 5). Pressing Return normally moves the cursor to the beginning of the next line.
⌫ backarrow key	Pressing the ⌫ key normally sends a DEL (delete) character. Many applications use DEL to erase one character to the left of the cursor. You can make the ⌫ send a BS (backspace) character instead of DEL. You use the backarrow key feature in the Keyboard Set-Up screen (Chapter 5).
Space bar	Pressing the space bar sends an SP (space) character. You use spaces to separate words or move the cursor forward.
Compose Character (left and right)	These are prefix keys, used to generate characters that do not appear as standard keys on your keyboard. See Chapter 6. On the German keyboard, the Compose Character key is replaced by Group Shift and Alternate Shift.
Group Shift Alternate Shift (German)	You use Group Shift as a prefix or modifier key, to type the characters on the right half of keycaps. See Chapter 6. Alternate Shift is a modifier key, used to generate a no break space (NBSP) or soft hyphen (SHY) character. Alternate Shift + space bar = NBSP character. Alternate Shift + - = SHY character.
Alt Function (left and right)	You use Alt Function with other keys, to select alternate functions defined by your application software. The Alt Function keys send unique function sequences to the host, when they are pressed or released. For more information, see the VT420 Programmer Reference Manual.

Editing Keypad

The editing keypad has four arrow keys and six editing keys.

Pressing an arrow key normally moves the cursor in the direction of the arrow. For example, pressing the key moves the cursor down one line.

You can use the editing keys in several ways.

• For set-up functions (Chapter 5)
• For copying and pasting text between sessions (Chapter 7)
• For panning up or down on a page, or for changing the size of a window on the screen (Chapter 7)
• For special functions defined by application software

Numeric Keypad

Numeric keypad keys often have functions assigned by application software, especially PF1 to PF4. See your application software manuals for information about those keys.

You can use the numeric keypad to enter numeric data as you would with a calculator. Programmers can use this keypad to do hexadecimal compose sequences. See "Hexadecimal Key Sequences" at the end of Chapter 6.

You can choose the keypad mode from the General Set-Up screen.

NOTE: The German keyboard dialect does not affect the application keypad mode.

Top-Row Function Keys

Predefined Keys

The first five top-row keys, F1 to F5, are predefined to perform the following functions. Normally, you do not change these functions. If needed, you can change the functions from the Keyboard Set-Up screen (Chapter 5).

User-Defined Keys and Application-Specific Keys

The function of the remaining top-row keys (F6 to F20) often depends on your application software. Refer to your application software manuals for a description of key functions. You can also define the function of these keys yourself.

Data Processing Keys

Most versions of the LK401 keyboard have some keys with characters on the left half and right half of their keycap. Normally, you use the characters on the left half of the key. These are called typewriter characters. The characters on the right half are for data processing use.

You can set these keys to send their typewriter or data processing characters, by using the typewriter/data processing feature on the Keyboard Set-Up screen (Chapter 5). One exception is the North American/United Kingdom keyboard.

# £ Key

The North American/United Kingdom standard keyboard has only one key with three characters.

To use the £ symbol, you select the British Keyboard setting in the Set-Up Directory screen. To use the # symbol, you select the North American Keyboard setting. There are no separate data processing legends on the North American/United Kingdom keyboard.

Compose Characters

You can type compose sequences to display many more characters than those shown on the keycaps. For example, you can display accented letters. Chapter 6 describes how to use compose sequences.

Indicator Lights

The keyboard has two indicator lights, hold and lock. When they are activated, Hold and Lock appear on the keyboard indicator line.

	Turns on or off when you press the F1 (Hold) key.
	Turns on or off when you press the lock key.

Audible Indicators

The keyboard has two audible indicators, a keyclick and a bell. You can use a margin bell, warning bell, or both. You select the keyclick and bell setting from the Keyboard Set-Up screen (Chapter 5).

Keyclick

You hear the keyclick sound each time you press a key that sends a code or causes the terminal to take some immediate action. If a key is autorepeating, the keyclick will repeat once for each character or key sequence sent. Keys do not click under the following conditions:

• You press Shift or Ctrl. These keys never click except when Shift is leaving the shift-lock state.
• You select Keyclick Off in the Keyboard Set-Up screen.
• You press a key or key combination that does not have a function under the current operating conditions. Examples: F6 to F10 in VT100 mode; invalid control combinations; and keys that generate 8-bit codes, when you use 7-bit national replacement character sets.
• The keyboard Wait indicator is on. The terminal is not accepting keystrokes because the host has reset keyboard action mode, or sent XOFF to the terminal and the keyboard input silo is full. You can manually clear the wait condition by selecting Clear Comm in the Set-Up Directory screen.

Bell

The bell tone is a beeping sound. You can use the bell as a margin bell, warning bell, or both.

Margin Bell

This bell sounds when the cursor is eight characters from the right margin.

Warning Bell

This bell sounds for any of the following conditions:

• During the power-up self-test
• When the terminal receives a bell (BEL) character from the host system
• After a compose character error
• When SSU errors occur (The bell rings twice.)
• If an NVR error message appears at the bottom of the screen (See Table 4-2.)

Keyboard Indicator Line

The keyboard indicator line appears at the bottom of the screen, below the status line. When you use two sessions, there is only one keyboard indicator line for both sessions.

The keyboard indicator line displays text in the smaller, 132-column font and appears in the same video background as the main display.

Keyboard Indicator Line Fields

The keyboard indicator line has six fields that show you:

• Which session the keyboard is connected to (the active session)
• Whether or not the inactive session has been updated
• When the screen is on hold or in a wait state
• When the F1 (Hold), Compose Character, Group Shift (German keyboard), or lock keys are active

Table 4-1 describes each field.

Status Line

The VT420 screen can display a status line that provides information about the terminal's current operations. If you are running one session, the status line appears at the bottom of the screen. If you run two sessions, a default status line appears at the bottom of each session. By default, the status line is disabled.

You can select when to display the status line. You can also let host applications write messages on the status line. To make these selections, you use the status display feature in the Display Set-Up screen (Chapter 5).

The status display feature has three settings.

NOTE: The VT420 uses separate set-up settings for each session. Any changes you make only apply to the session you are in. If you want to change a set-up setting for two sessions, you must make the change in each session.

Status Line Fields

The default status line has four fields that show you:

• The page number of the page displayed
• Cursor position
• Printer status
• Modem status

Table 4-2 describes each field. When you select a host-writable status line, applications on your host system can use the status line to send you messages.

You can display the status line in English, French, or German. Use the set-up language feature in the Set-Up Directory screen to select the dialect.