Cool! Thanks for the info, how did you figure that out anyway? I know there is a decoder for the Mac but never heard of one for an ImageWriter. Pretty cool!!
I'm not 100% sure what it is or was but its suppose to advance the ribbon and twisting the knob did nothing. Maybe genuine Apple ones were prone to this at this age?
There was a serial version and an appletalk version, so you may want to wait and see how you're going to use the printer. I don't know if Microspot still has both versions.