Editing Intel MCS-51 (section)

== Microarchitecture ==
The microarchitecture of the Intel MCS8051 is proprietary, but published<ref name="mcs51um">{{cite book |title=MCS-51 Microcontroller Family User's Manual |date=1994 |publisher=Intel |location=publication number 121517 |url=http://datasheets.chipdb.org/Intel/MCS51/MANUALS/27238302.PDF |access-date=17 May 2021 |ref=mcs51um}}</ref> features suggest how it works. It is a [[multi-cycle processor]]. The MCS8051 used 12 clock cycles<ref name="mcs51um"/> for most instructions. Many instructions utilize an accumulator.<ref name="mcs51um" /> In contrast, most compatible computers execute instructions in one to three cycles, except for the multiply and divide instructions. The much higher speed is a major reason why these have replaced the MCS8051 in most applications.

Each interrupt has four priorities.<ref name="mcs51um" /> Within each priority, the interrupts of devices are in a fixed priority.<ref name="mcs51um" />