Yep, It has a 1 1/8" head tube.
For those that aren't aware, the Tioga Avenger headset (aka "OS" or "1 1/8") was introduced in 1989, and Gary Fisher's Evolution headset (aka "EVO" or "1 1/4") was introduced in 1988. Both sizes were pretty common on 1990's era mountain bikes regardless of what you read on the web about 1" headtubes being dominant around that time.