The M8051 is a straightforward implementation of an 8-bit microcontroller and is clock for clock compatible with the classic Intel 87C51 and 87C52 devices. To achieve this precise compatibility, these designs use a 12 clock per machine cycle architecture, featuring two memory accesses in each machine cycle. Instructions typically take either 12 or 24 clock cycles to execute. Only the multiply and divide instructions take longer, consuming 48 clock cycles.
The M8051 is typically used in applications that require the microcontroller core to be a drop-in replacement for a discrete 8051 device. These designs tend to be easier to adopt than optimised 8051 implementations, because they maintain precise clock cycle compatibility with older devices. Preservation of the precise clock-to-instruction ratio is often a requirement where existing software relies on timing relationships with peripheral devices such as interrupts, counters, timers etc.