Microprocessor - 8085 Control Instructions

Following is the table showing the list of Control instructions with their meanings.

Opcode	Operand	Meaning	Explanation
NOP	None	No operation	No operation is performed, i.e., the instruction is fetched and decoded.
HLT	None	Halt and enter wait state	The CPU finishes executing the current instruction and stops further execution. An interrupt or reset is necessary to exit from the halt state.
DI	None	Disable interrupts	The interrupt enable flip-flop is reset and all the interrupts are disabled except TRAP.
EI	None	Enable interrupts	The interrupt enable flip-flop is set and all the interrupts are enabled.
RIM	None	Read interrupt mask	This instruction is used to read the status of interrupts 7.5, 6.5, 5.5 and read serial data input bit.
SIM	None	Set interrupt mask	This instruction is used to implement the interrupts 7.5, 6.5, 5.5, and serial data output.

microprocessor_8085_instruction_sets.htm