[Coco] Extended basic 1.1 command?

[Charlie]

I am trying to edit one of my old programs written on the Coco3 to run on my Coco1.

The program reads

120 IF BUTTON(0)=1 THEN 140
130 GOTO120

This detects if Joystick 0 button is pressed, if so goto 140...

I see that BUTTON is not a valid command in Extended Basic 1.1 in my coco1.

Can someone give me a simple example how to do the equal of these two program lines in the older Extended Basic?

Thanks.

Charlie