Difference Between Microprocessor and Micro Controller

Parameter	Microprocessor	Micro controller
Description	It is Multipurpose, Programmable device that accepts digital data as input from external input unit, processes it as per instructions in its memory, and provides results as output at external output unit.	It is a Self Contained System with a processor core, memory, and peripherals and can be used as embedded system.
Software Protection	Software Protection is less achieved in Microprocessor based systems.	Micro controllers offer more software protection by locking the on chip memory and is made protected from external circuit.
Input/output Devices	Keyboard, Mouse, Screen, disks, printers etc.	Switches, Relays, LEDs, LCD Displays, radio Frequency devices ,Sensors
Cost	High, Because Devices like memory, disks, and interfaces are connected externally and has to be purchased separately.	Decreased net cost of the embedded system as a whole, Because no needs to connect external devices like Read/Write Memory, Timers etc., unless you desire to create something beyond the limit.

Intel 8255 (Programmable Peripheral Interface)

Intel 8255 is a PPI (Programmable Peripheral Interface) and is used to interface Peripheral devices to microcomputers. It can be programmed in a variety of ways as per Programmer Requirements. It has two versions 8255A and 8255B. Both of them are similar in general description but are different in their electrical characteristics.

Intel 8255 Consists of Three 8 Bit Ports: Port A, Port B and Port C. The Port C is further divided into two 4 Bit Ports: Port C_UPPER and C_LOWER. These three ports are divided into two groups for the purpose of Programming:

Group A: This Includes Port A (PA₀-PA₇) and 4 MSBs of Port C (PC₄-PC₇).

Group B: This Includes Port B (PB₀-PB₇) and 4 LSBs of Port C (PC₀-PC₃).

Features of 8086 Microprocessor

1) It is 16 bit N- Channel HMOS (High Speed MOS) processor. Its CMOS version 80C86 is also available.
2) Intel 8086 Draws 360 mA on 5V whereas 80C86 draws 10 mA at 5 V.
3) It can operate at standard temperature Range 32˚ F to 180˚ F and at extended temperature range 40˚F to +225˚F.

Instruction Cycle

Before knowing instruction set we have to know two things i.e. opcode and operand. Operand is the data on which operation is to be performed and opcode is the operation which has to be performed. Thus the time taken to fetch the opcode from the memory and execute the operation on operand is a complete Instruction Cycle. Instruction cycles consist of fetch cycle and execute cycle.

IC (Instruction Cycle) = FC (Fetch Cycle) + EC (Execute Cycle)

Instruction set of 8085

Instruction set is a collection of instructions that a processor can execute. Microprocessor operates on these instructions. If an instruction that is not in the instruction set of a particular microprocessor, is invalid for that processor. Each instruction in 8085 belongs to a particular group depending upon the task they perform. These Instructions are classified as:

1) Data Transfer Group: These Instructions are used to transfer data from one register to another, memory to register or from register to memory. E.g. MOV, MVI, STA, LXI, LDA, LHLD, SHLD, LDAX, STAX, XCHG etc.

Intel 8085 Block Diagram

Intel 8085 consists of following three main sections:

Arithmetic and Logical Unit:- The main function of ALU is to perform arithmetic and logical operations such as Addition, subtraction, Logical AND, Logical OR, Complement, Increment, Decrement, Shift Operations etc.

Timing and Control Unit: - Generation of timing and control signals for the execution of instructions is done by this unit. It controls and monitors flow of data between CPU and I/O devices. It works as brain for Computer System.X1, X2, Clock Out, ready, ALE, HOLD, HLDA are some examples of signals generated by this unit.

Features of 8085 Microprocessor

Intel 8085 is an 8 bit Microprocessor developed by Intel in 1977.main Features of this Processor are as follows:
1) It is 8 bit, NMOS Microprocessor.
2) It has 16 Address Lines and 8 bit data bus is multiplexed with lower part of 8 bit address lines to limit no. of pins to 40.
3) It operates at Single +5 V DC Supply.
4) It consist of following Register sets: