The 8085 instruction set can be classified into the following five functional headings.
Group I - DATA TRANSFER INSTRUCTIONS:
Includes the instructions that moves ( copies) data between registers or between memory locations and registers. In all data transfer operations the content of source register is not altered. Hence the data transfer is copying operation.
Ex: i) MOV A,B ii) LDA 4600 iii) LHLD 4200
Group II - ARITHMETIC INSTRUCTIONS:
Includes the instructions which performs the addition, subtraction, increment or decrement operations. The flag conditions are altered after execution of an instruction in this group.
Ex: i) ADD B ii) SUB C iii) INR D iv) INX H
Group III - LOGICAL INSTRUCTIONS:
The instructions which performs the logical operations like AND, OR, Exclusive-OR, complement, compare and rotate instructions are grouped under this heading. The flag conditions are altered after execution of an instruction in this group.
Ex: i) ORA B ii) XRA A iii) RAR
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.
Ex: i) JZ 4200 ii) RST 7 iii) CALL 4300
Group V - MACHINE CONTROL INSTRUCTIONS:
Includes the instructions related to interrupts and the instruction used to halt program execution.
Ex: i) SIM ii) RIM iii) HLT
The 74 basic instructions of8085 are listed inTable-2.1. The opcode of each instruction, size, machine cycles, number of T -state and the total number of instructions in each type are also shown in table in next page. The instructions affecting the status flag are listed in table followed.