INSTRUCTION SET OF INTEL 8085




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.





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