I don't have photos of my 800 handy, but here's a pic showing one of the original shifters, on the same year/model being sold on La Crosse CL:

They're simple thumb shifters, that you rotate to each click stop for each gear. "Trigger shifter" usually refers to the kind where you push one of two levers/buttons (or a single trigger you push one direction or the other), and the trigger/lever springs back to position after it shifts.

Triggers are cool and quick and handy when they work, but the depend on springs and ratchets and pawls to work, and when the grease in them gums up, the triggers get "flaccid" and don't shift. That's when you need to clean/degrease and then re-lube them.

True "thumbies" simply rotate, much like the old stem or downtube shifters on road bikes (but located up on the bar). There's click stops for each gear position, but no other complex mechanism, so they're more reliable and easier to maintain, esp. long term. It's also why they're often favored for winter daily drivers, since they're less likely to flake out in the cold.

The MTB/hybrid market seemed to shift (no pun intended) from thumbies to triggers somewhere around '91 (then grip-shfiters several years later). But you can still get brand new Sunrace brand thumbies today.