[Karliss]

Arguing about hard definitions differentiating microprocessor from microcontrollers based on single feature is pointless. It's a vague product/marketing category for certain usecases. There will be group of features that are more likely included or not included, but for most of them there will likely be exceptions. And the set of available features available MCUs and microprocessors change over the time. As technology improves both microcontrolers and processors are gaining new capabilities.

* MCUs usually have program memory builtin. But then there chips like RP2040 or ESP32 which while considered MCUs are used with external Flash memory chips for storing the firmware. * MCUs usually have builtin RAM. But there are also some capable of directly using external RAM. * Then there are things like apple M1 chips, with a lot of stuff builtin you still don't call them MCU. * A bunch of ARM application processors/SOCs/Microprocessors might have enough resources builtin that they could be used as more or less standalone microcontrollers, without external RAM or flash memory. * some early microprocessors used external MMUs and it took some time until the processors settled on architecture that's closer to how we have things now * early personal computer processors were in a weird category in terms of price and processing power, in certain time period it wasn't impossible that similar microprocessor chip was used both for as main computer CPU and also for peripheral devices.

The microprocessor name in my opinion at this point is slightly outdated. It's not like anyone beside hobbyists is making non micro processors out individual relays, transistors or logic chips.

[kragen]

mostly i agree; it's mostly a marketing distinction rather than a technical one

actually i think non-micro (multi-integrated-circuit) processors are becoming popular again. the 'microprocessor' moniker wasn't coined to distinguish processors built out of discrete transistors from processors built out of integrated circuits; that was the 'second-generation computer' vs. 'third-generation computer' distinction back in the 01960s. what made a microprocessor 'micro' was that it was a chip instead of a circuit board