[Coco] Color BASIC 1.3 How to get joystick button input

[Ben]

Hi,

I'm new to programming on the coco. I have a coco 2 with Color BASIC 1.3. It 
does not seem to support the button(0) function. I've looked through some 
pokes and did not find one to get the button values. Is there a way to get the 
button values from a deluxe joystick?

Ben