Casio FX-820P Pocket Computer with built in printer

[Jeff_Birt]

This is the wildest gear train I have ever seen on a (thermal) printer. The gear at an angle is supposed to be that way. It rotates the 5-tooth cog which feeds the paper. The motor only rotates 1 direction and the printhead is pushed by grooves in a drum which are sort of like overlapping sine waves, so when it reaches the end in one direction, it follows the other phase sine and moves backwards.

The computer part works, runs on two CR2032s but I need to build a new NiMh battery pack for the printer (4xAAA in series).