The 8085 instructions can be classified into the following five functional groups.
Group I – Data Transfer Instructions: Includes the instructions that move (copy) data between registers or between memory location and register. In all data transfer operations, the content of the source register or memory is not altered. Hence the data transfer is a copying operation.
Group II – Arithmetic Instructions: Includes the instructions which perform addition, subtraction, increment, or decrement operations. The flag conditions are altered after the execution of an instruction in this group.
Group III – Logical Instructions: The instructions which perform the logical operations like AND, OR, EXCLUSIVE-OR, complement, compare and rotate instructions
are grouped under this heading. The flag conditions are altered after the execution of an instruction in this group.
Group IV – Branching Instructions: The instructions that are used to transfer the program control from one memory location to another memory location are grouped under this heading.
Group V – Machine Control instructions: Includes the instructions related to interrupts and the instruction used to halt program execution.