I have the Bernina 430, one step down from yours, and it has the button. It's two buttons up from reverse. It's dark blue with a solid dot and an open circle. I don't use it much myself.

It really came in handy when the munchkin (6 year old) next door wanted to learn to sew. She was too little to reach the foot pedal, but could sew a nice straight seam. We started with dog beds for the shelter and now she can do tote bags with ease. My one rule was "Thou shalt not touch the rotary cutter!" I do the cutting and she does all of the stitching for her projects - so far that includes dog beds, tote bags, placemats (using selvages), pillow cases, and a skirt for herself. Now that she is 7 and taller, she uses the start/stop button on my Elna, but uses the foot pedal on the serger. Her mother just shakes her head in dismay - she doesn't sew anything.

I use mine all the time, when I go sew somewhere else with my traveling machine, I find myself reaching for the On/OFF button, which is not there.

yes you do have a stop/start button. I have a 440 use it all the time...look on the front at the three left lowest buttons.
It is a black button with circle and a dot in white just above the reverse pattern button which is just above the reverse stitch button. Or look in your manual and you will see it marked on the page that shows you all your machine parts names.

I've never used it really but think I tried it out one time. I was told it's mainly for handicapped people but I'm sure anyone could use it.....I was just using it to try it out.
I was missing the control of the foot but they both have good features.
At least the foot pedal wasn't sliding all over my carpet....

If you have a Babylock, the footpedal has to be unplugged.

Never use the foot pedal unless I am free motion quilting..... I love it.

I use mine for paper piecing. If I'm going to do small pieces on a lot of different sections, I use it. Otherwise my foot gets sore with all the starting and stopping.

My dealer told me to use the button for FMQ but in my class they told me just the opposite. My 1966 Elna didn't have a button and I don't like the one on my Janome. Too slow on the uptake!

not sure where my foot pedal is. love the start/stop button!