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What’s the difference between a microcontroller and a microprocessor?

Please inform me of the difference, if any.

  • 3
    \$\begingroup\$ Nick, when you start typing the title of a new question you get a list of questions with similar titles. Please read them. The question I linked to as duplicate was the first in the list when I typed the title of your question. \$\endgroup\$
    – stevenvh
    Oct 16 '12 at 9:53
  • \$\begingroup\$ @stevenvh this question appears different to me? He's not mentioning microcontrollers anywhere. \$\endgroup\$
    – exscape
    Oct 16 '12 at 9:56
  • 2
    \$\begingroup\$ @exscape - In the answers to that question there's a couple of times mentioned that a microprocessor is just a CPU. \$\endgroup\$
    – stevenvh
    Oct 16 '12 at 10:03
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    \$\begingroup\$ Thank you, I understand. I thought microcontroller had nothing to do with it, but it is answered there. \$\endgroup\$ Oct 16 '12 at 10:35

A CPU (central processing unit) is the part of a computer that executes instructions. This can be implemented using a single IC, a number of ICs, discrete transistors or a room full of vacuum tubes.

A microprocessor is a single-chip implementation of a CPU.

Nowadays pretty much all CPUs for general use are microprocessors, causing the two terms to be practically synonymous.

  • \$\begingroup\$ Is it "fair" to view microprocessor as a sort of umbrellaterm encompassing CPUs, GPUs, procecssors that specialy in accelerating machine learning algorithms, etc. ..? I have read this article. \$\endgroup\$ Feb 5 '21 at 16:29
  • \$\begingroup\$ So the reason why "almost all CPUs are microprocessors" is because almost all CPUs are integrated on a single chip? \$\endgroup\$ Feb 5 '21 at 16:40
  • \$\begingroup\$ IC = Integrated Circuit. For anyone who didn't know. \$\endgroup\$
    – gignu
    May 30 '21 at 8:20
  • \$\begingroup\$ What about things like Network processing Unit (NPU) , Audio Processing UNIT (APU) and Graphic Processing UNIT (GPU) ? \$\endgroup\$
    – quantum231
    Aug 7 '21 at 15:14

Do read the question (and answers) stevenh linked to, but your question is somewhat different.

A Central Procession Unit (CPU) is the part of a computer that sequences and executes instructions. Other parts in the traditional computer architecture are the memory and the I/O.

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In the stone age days of computers a mainframe's CPU's occupied multiple cabinets. Later a minicomputer's CPU occupied one or a few PCBs. The next step was to integrate a CPU on a single chip. That is what we call a microprocessor (uP).

From there the development forks:

  • the CPU-on-a-chip is made more powerfull (faster, parallel execution, fast execution of complex instructions like divide and transcendentals), a cache is added, more CPU's are combined in one chip, etc. This results in the (mainly Intel) super-microprocessors of today.
  • a moderately powerfull CPU (more powerfull than those in a uC, but less than those in a desktop CPU) is combined with a small boot ROM and a set of complex peripherals, like a video/lcd subsystem, mpeg decoder, wired or wireless ethernet interface, USB intefaces, etc. to cerate a 'system-on-a-chip'. These chips form the hart of modern set-top boxes and the small Linux systems (Beaglebone, Raspberry Pi, etc.) derived from them.
  • The CPU is combined with memory and I/O on the same chip, creating a complete computer on a single chip. This is called a microcontroller (uC).
  • \$\begingroup\$ Upvoted for saying the same as myself, but in greater detail. \$\endgroup\$ Oct 16 '12 at 10:10
  • \$\begingroup\$ Where does System-on-a-chip fits in all these? I guess it's further development for the second type? \$\endgroup\$
    – Lie Ryan
    Oct 16 '12 at 13:53
  • \$\begingroup\$ No taxonomy is perfect, reality always has its way. I would classify the typical System-on-a-chip with the first category, because it can not run without external RAM and ROM. But feel free to defined a third category. \$\endgroup\$ Oct 16 '12 at 14:24
  • \$\begingroup\$ I added a 3d category :) \$\endgroup\$ Sep 5 '15 at 10:07
  • \$\begingroup\$ So in summary, a microprocessor is a CPU integrated on a single chip? I.e. the CPU is a microprocessor if it is integrated on a single chip? \$\endgroup\$ Feb 5 '21 at 16:36

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