VT100.net: Digital VT102 User Guide

Table 1-1 Keyboard Locked Condition
Cause | Method of Clearing
--- | ---
Terminal not connected to computer. Communication line signals are not correct for communication. | Cleared when a connection exists between computer and terminal. Check CTS and DSR indicators to determine if a connection exists.
Half-duplex communication is selected (by modem control SET-UP feature) and terminal is receiving characters. Terminal cannot transmit characters when receiving characters in half-duplex. | Cleared when line turns around and terminal can transmit characters.
Characters are typed into terminal faster than they can be transmitted. | Cleared when terminal transmits characters in keyboard character buffer to computer.
A print operation selected while offline. | Cleared when print operation ends.
Computer turns off keyboard. | Computer turns on keyboard.
NOTE: Entering and exiting SET-UP with KBD LOCKED on erases the keyboard character buffer and cancels printing or print operation requests.