IBM PCjr Manual page 31

It looks as if a keyboardis being built. See how closely
those four blocks resemble the four cursor control keys
you just pressed? Notice the pattern they make on the
screen.
Press the Cursor Right key again -
three or four times - and watch the
screen closely.
Look at the small Une moving across the top of your
screen as you press the Cursor Right key.
Press the Cursor Left key several
times.
Remember when we told you about the cursor? Well,
this is a cursor. Cursors come in different styles.
Some, like this one, are little Unes. Some are blocks.
Some are bright, and some will even blink at you to
catch your eye. But they all do the same thing - they let
you know where you can place something on the
screen.
Getting Started 2-15