It has been quite some time since integration capabilities first allowed the processor, memory, and I/O to all go on one chip and the name changed from microprocessor to microcontroller. 

The problem in the early days was the development process–it was quite feasible to get a large quantity of a device built with a fixed program permanently integrated (if you were using a micro in a high-volume application such as an engine controller in an automobile), but getting just one device with a new iteration of a program you were developing was a different matter. Continue reading →