Microcontrollers are specialized computers typically used for a single purpose. Examples of microcontrollers commonly used these days include:
- Teensy - this is what is used for the for the multiple stepper motor control system
- Tic - this is what is used for the MDF Rose Engine Lathe 2.0 for the spindle-only stepper motor control system
And there are many more.
Typical uses for a microcontroller is in automating movement such as driving a stepper motor. They are typically integrated with sensors like limit switches. For these reasons, they are found in many household items, including toasters!
More information is available on Wikipedia at Microcontroller.
Disclaimer: eMail comments to me at OTBookOfKnowledge @ Gmail.com. The process of woodturning involves the use of tools, machinery and materials which could cause injury or be a health hazard unless proper precautions are taken, including the wearing of appropriate protective equipment.