The program in Listing 1 uses a pseudo-RETI instruction to provide a five-priority-level interrupt system for the 8051P microcontroller. The interrupt-priority order, from high to low, is INT0 IT0 ...

The 8051-compatible microcontrollers are equipped with up to two inputs that may be used as general-purpose interrupts. A simple way to increase the number of interrupt inputs is shown in the figure.

Suppose for a moment that you're an engineer designing a new 8051-based product. Not unexpectedly, the application's code size will greatly exceed the 64KB architectural limit of the 8051's program ...

The 8051 is an accumulator-based design with 255 instructions. A basic instruction cycle takes 12 clocks; however, Dallas Semiconductor redesigned the instruction-execution circuitry to reduce the ...