Appendix A

VT220/VT102 Differences

This appendix describes the major differences between a VT102 terminal and the VT220 terminal operating in a VT100 mode.

Difference Area VT102 VT220
LED indicators Programmable Not Programmable
Alternate character ROM Socket for OEM-supplied character ROM Down-line-loadable character set
Screen freeze NO SCROLL key Hold Screen key
Printer port connector 25-pin 9-pin
Screen refresh 50/60 Hz 60 Hz only
Set-up Display in set-up "bits". Display in three different languages. Different display. Has no effect on software.
RIS function Performs power-up self test Does not perform power-up self test
Off-Line/local mode Off-Line mode disconnects modem. Local mode does not disconnect modem.
Communication Full duplex and half duplex Full duplex only. Does not affect software.
Transmit speed limit is 60 characters/second regardless of baud rate. Optional transmit speed limit is 150 characters/second.
Passive or active 20 mA is selectable. Only has passive 20 mA.
Terminal ID Responds to primary device attributes with ESC [ ? 6 c sequence.

You can select the DA response in set-up. The standard VT220 response is

CSI ? 62;1;2;6;7;8;9 c


Secondary device attribute not supported. Responds to secondary device attribute with
CSI > 1;Pv; 0 c
Pv is firmware version number.