What is instruction set? Explain different kinds of instruction set used in 8085 microprocessor.

What is instruction set? Explain different kinds of instruction set used in 8085 microprocessor.

THE 8085 INSTRUCTION SETS
An instruction is a binary pattern designed inside a microprocessor to perform a specific function (task). The entire group of instructions called the instruction set. The 8085 instruction set can be classified into 5-different groups:
Data Transfer Instructions
Arithmetic Instructions
Branching Instructions
Logical Instructions
Control Instructions

DATA TRANSFER INSTRUCTIONS
It is the longest group of instructions in 8085. This group of instruction copy data from a source location to destination location without modifying the contents of the source. The transfer of data may be between the registers or between register and memory or between an I/O device and accumulator. None of these instructions changes the flag.

ARITHMETIC INSTRUCTIONS
The 8085 microprocessor performs various arithmetic operations such as addition, subtraction, increment and decrement. The arithmetic operation add and subtract are performed in relation to the contents of accumulator. The features of these instructions are
1.They assume implicitly that the accumulator is one of the operands.
2.They modify all the flags according to the data conditions of the result. They place the result in the accumulator.
3.They do not affect the contents of operand register or memory. But the INR and DCR operations can be performed in any register or memory. These instructions
4.Affect the contents of specified register or memory.
5.Affect the flag except carry flag.

BRANCHING INSTRUCTIONS
The microprocessor is a sequential machine; it executes machine codes from one memory location to the next. The branching instructions instruct the microprocessor to go to a different memory location and the microprocessor continues executing machine codes from that-new location.

LOGICAL INSTRUCTIONS
A microprocessor is basically a programmable logic chip. It can perform all the logic functions of the hardwired logic through its instruction set. The 8085 instruction set includes such logic functions as AND, OR, XOR and NOT (Complement).