IBM PCjr Manual page 37

Let's use it now.
Press the Enter key and watch the
top of your screen.
What happened to your name??? The printing is gone,
and the cursor is back at the upper left comer of your
screen. Don't worry, though. It isn't lost forever. The
Enter key just "entered" your name into the computer's
memory. Later, after we introduce more of the keys,
we'll show you what a good memory the computer
reaUy has.
The next few keys you wiU use confuse some people.
These are the keys that give you the lowercase "o", the
uppercase "O", and the zero. Let's look at them on the
screen.
Getting Started 2-21