I am just starting out on a journey to understand microcontroller and microprocessor design. Have read briefly on their differences (ARM7 and Intel i3, i5 & i7). Couldn't find any information on their differences in architecture. for example, ARM7 has 21 external interrupt pins. but couldnt find definite information about intel's external interrupt pins. or how On-chip static ram is 8 kb-40 kb, on-chip flash memory is 32 kb-512 kb, the wide interface is 128 bit, or accelerator allows 60 MHz high-speed operation for ARM7. couldn't find any corresponding information on intel's processors.

  • \$\begingroup\$ welcome to the world of buzzwords \$\endgroup\$
    – fraxinus
    Mar 18, 2021 at 10:05
  • \$\begingroup\$ Usually all the juicy details are in the Technical Reference Manual... \$\endgroup\$
    – MarkU
    Mar 18, 2021 at 10:06
  • 7
    \$\begingroup\$ I think you're comparing apples with hotdogs here. A microcontroller with embedded flash memory, SRAM & peripherals is a very different beast to a PC microprocessor. \$\endgroup\$
    – brhans
    Mar 18, 2021 at 10:12
  • 1
    \$\begingroup\$ Take some computer architecture course in UDEMY/Coursera. \$\endgroup\$
    – Mitu Raj
    Mar 18, 2021 at 11:20
  • \$\begingroup\$ I recommend that you visit this CARDIAC site and also pick up a book called Bebop BYTES Back: An Unconventional Guide to Computers. The first is from a Bell Labs pair of authors and is designed to teach bare machine programming, including bootstrapping ideas, to young students. The second provides a quick overview for self-study on computer architecture. Obviously, there are some very good textbooks. But these often need the support of a teacher/aides to absorb well. \$\endgroup\$
    – jonk
    Mar 18, 2021 at 18:46

2 Answers 2


ARM7 has 21 external interrupt pins

No, a generic ARM7 has two external interrupts: IRQ and FIQ.

The problem here is "architecture" versus "implementation". ARM7 is an architecture. LPC2148 (for example) is an implementation of that architecture. The implementation has pins, cache, etc. You got that information from this page, perhaps?

Intel handle interrupts very differently. A datasheet for Intel. It has no external interrupt pins - instead it has a PCI-E bus, and messages on that bus can be translated into interrupts.

  • \$\begingroup\$ To be a bit pedantic, the ARM7 series are actual implementations. Confusingly, the series implements the ARMv3, ARMv4, and ARMv5 architectures. The ARMv7 architecture is split into A, R, and M for Application, Realtime, and Microcontroller. Implementations of the respective v7 architectures are, for example, Cortex-A15, Cortex-R5, Cortex-M4. \$\endgroup\$
    – awjlogan
    Mar 18, 2021 at 13:35

As @pjc50 noted, you are confusing architecture vs implementation. Also, the ARM implementation you noted is a microcontroller or SOC (system on chip). This is why it has RAM, FLASH, interrupt controller, etc. on chip.

On the other hand, the Intel chips mentioned are microprocessors. All that is on-chip is basically the CPU, cache memory and maybe on-board graphics. Everything else, interrupt controller, RAM, non-volatile storage, etc, is off-chip, in the “chipset”, DDR RAM modules and external storage.

  • \$\begingroup\$ In terms of 'architecture', there's the ISA (instruction set architecture) which describes things like the register set and the available instructions. This is distinct from the actual hardware implementation. The Intel i3,5,7 all implement much the same ISA, but the hardware is different due to the market wanting a range of cost/performance options. Similarly with the ARM - the hardware implementation ranges from low end devices you might find in a watch all the way up to the likes of the Apple M1 which competes with the Intel offerings in terms of compute performance. \$\endgroup\$
    – Kartman
    Mar 18, 2021 at 11:48

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