When the idea of transforming robots began to become popular in the early 1980's, it didn't take long for the toy designers to experiment with the concept of self-transforming toys. The Jumpstarters were released in 1985, part of the second year of the original Transformers line in the United States, but their origins go back a year or so earlier, to the Diaclone line in Japan, where these molds were released under the name "Baku-Ten Attack Robo." As best as I can tell, "Baku-ten" translates into "Blast Flip," which is an accurate enough description of how these toys work.
But first, the part you have to do yourself. As the first Transformers-related toys to be designed to change form on their own, it's no surprise that these toys are very simple. Topspin is featured here, but Twin Twist features exactly the same design and transformation. Fold the toy in half to create something that's basically a vehicle because the instruction booklet tells you that it is. That's all there is to it! Fold in half, and you're done.
Well, obviously that's not the big selling point of the toy. The big deal is that this thing's supposed to change forms on its own, right? To achieve this, pull back on the vehicle to trigger the spring-loaded wheels underneath, and let it go. The toy will roll forward on the floor until a catch (seen here on the toy's chest) is released, causing the legs to swing forward. Ideally, the legs should hit the ground with enough momentum to cause the robot to stand up and stay there in robot form, ready for battle. Well... almost. You do have to add the weapon yourself, of course.
Of course, all that assumes that everything works the way it's supposed to. Unfortunately, as often as not, the toy falls flat on its face rather than stand up like it should. Also, kids often had a tendency to try to change the toy back into robot mode without letting the wheels release that catch, causing the catch to be broken on many specimens. For this reason, Jumpstarters are easily mocked as Transformers toys. However, I really do think that any Transformers fan who appreciates the Generation One era ought to have at least one of these toys. There's the historical aspect, of course, being the first self-converting toys in the line. They're also incredibly cheap to get a hold of, because Hasbro apparently made a lot of them, and these toys aren't ones that most people have been holding on to all that tightly (just take a look on eBay, where Jumpstarters can be found for less than $10, even after shipping has been added). If nothing else, I think they just are good for a laugh, since even if watching the toy fall over doesn't amuse you, watching your cat chase after it is bound to be fun!