One feature of the 8051 core is the inclusion of a boolean processing engine, which allows bit-level boolean logic operations to be carried out directly and efficiently on select internal registers, ports and select RAM locations. Another feature is the inclusion of four bank selectable working register sets, which greatly reduce the time required to perform the context switches to enter and leave interrupt service routines. With one instruction, the 8051 can switch register banks, avoiding the time-consuming task of transferring the critical registers to RAM.