IBM PCjr Manual page 94

Look at your Keyboard Difference Chart.
In the left column, you see "Ctrl/Break (or Break)". If
you follow that line over to the IBM VCjr keyboard
column, you see that you get Ctrl/Break by pressing
the green bordered Fn key and the Break key with the
green stripe.
Press
f' '
1
then
'
That's all there is to it! You may want to spend some
time looking at the chart untU you feel comfortable with
it. Most of the key combinations are color coded on
your keyboard.
This chart has been reproduced on a card in the front of
this book. You can put this card beside your IBM PCyr
when you are using programs written for an IBM
Personal Computer keyboard.
4-8 Choosing Keys