VT100.net: Digital VT102 User Guide

# 4 Transmitted Characters

## General

This chapter describes the characters generated by the VT102 keyboard. The keys are divided into three groups: standard keys, function keys, and numeric keypad keys.

## Standard Keys

The keyboard generates American Standard Code for Information Interchange (ASCII) characters. The standard keys (Figure 4-1) generate lowercase ASCII characters when neither SHIFT or CAPS LOCK are down. These keys generate uppercase ASCII characters when either SHIFT or CAPS LOCK key are down. CAPS LOCK does not affect the nonalphabetic keys.

## Function Keys

The function keys (Figure 4-2) generate characters defined by the computer software or communication system. The following paragraphs describe the function keys.

### BREAK/HERE IS

This key generates a break defined by the computer system when the break enable feature is on. This feature does not affect other key sequences using BREAK.

Hold down SHIFT and press BREAK to generate a long break disconnect. A long break disconnect usually disconnects the terminal from the communication line. See Break in Chapter 6 for more information about breaks and long break disconnects.

Hold down CTRL and press HERE IS to transmit the answerback message. See Chapter 3 for more information about the answerback feature.

### Cursor Control Keys

In ANSI mode, with alternate (application) keypad mode selected, the cursor keys generate either application or cursor control sequences. Cursor key mode selects the type of sequence.

With numeric keypad mode selected, the cursor keys generate ANSI cursor commands. The computer selects both cursor key mode and keypad mode. See Cursor Key Character Selection in Chapter 5 for more information.

In VT52 mode, the cursor keys only generate VT52 cursor control sequences. Table 4-1 lists the ANSI and VT52 compatible cursor key characters.

### Control Character Keys

Figure 4-3 shows the keys that generate control characters. You can generate control characters in two ways.

- Hold down CTRL and press any unshaded key in Figure 4-3.
- Press any shaded key in Figure 4-3 without using CTRL. These dedicated keys generate control characters without the use of CTRL.

Table 4-2 lists the control characters generated by the keyboard. Different computer systems may use each control character differently.

NOTE: The VT102 generates some control characters differently than previous DIGITAL terminals. Table 4-3 lists the changes.

## Numeric Keypad Keys

These keys generate characters selected by the ANSI/VT52 feature and alternate (application) keypad mode. The computer selects application keypad mode. See Keypad Character Selection in Chapter 5 for more information.

In numeric keypad mode, the numeric keypad generates the numeric, comma, period, and minus sign characters used by the main keyboard. In application keypad mode, the numeric keypad generates control functions. Table 4-4 lists the characters generated by the numeric keypad.