TRX200S ignition
 

I have a basket case TRX200S (1980 something?)that I'm trying to get running. I have a lot of experience with cars, but only a couple motorcycles. I was checking to make sure the 200 was firing correctly and found that it fires off a crank trigger. How the heck does it know if it is on the compression or exhaust stroke? Does the ignition unit only fire every other signal? My 1971 CB175 & 1985 ATC 200S fired off cam like normal. I don't have a repair manual yet, which I will be getting. I was just trying to get the basics out of the way. Anybody have an idea?
Thanks.