AT&T 6300 Programmer's Manual page 32

Getting Started
2-14
INS
Switches into or out of Insert Mode. If Insert Mode is off
(Overwrite Mode on), then it turns it on. If Insert Mode is on,
then it turns it off (sets Overwrite Mode). The Insert Mode cursor
is a half-height blinking block (in Text Mode) and is a
blinking triangle to the left of the character (in Graphics Mode).
Overwrite mode is indicated by a different cursor, which is a
slow-blinking under line. In Insert Mode, the characters im-
mediately above, together with· those following the cursor,
move to the right as characters are inserted at the current
cursor position. Line folding is observed; that is, as charac-
ters disappear off the right side of the screen, they return on
the left on the following line.
When in Overwrite Mode, characters typed will replace
existing characters on the line.
Insert Mode is turned off when you press the iNS key again,
or if you press any of the cursor movement keys, or CR.