what is microprocesor, features of 8085 microprocessor, bus structure and architecture diagram of 8085 microprocessor.

                    WHAT IS MICROPROCESSOR

INTRODUCTION :- The microprocessor is a programmable integrated device that has computing and decision making  capacity. it is a multipurpose programmable clock driven register base electronic device, that reads binary instructions for a storage device called "memory" accept binary data as  input & process data according to those instructions and provides results as output.

ORGANISATION OF A MICROPROCESSOR BASED SYSTEM:-

Microprocessor based system includes three components microprocessor input, output & memory.

this component are organised around a common communication path called a Bus.

Microprocessor can be divided into three segments, ALU, Register array & control unit:-

• ALU: In this various computing function  are performed on data.   the ALU unit performs arithmetic operation such as addition, substraction & logic operation such as AND, OR & XOR.

• Register array: it consist of various register identify by latter such  B,C,D,E & H,L. this register are used to store data temporarily during the execution of  a program are accessible to the user through instruction.

• Control unit:  the control unit provides a necessary  timing and control signal  to all the operation. it control the flow of data between the microprocessor, memory and peripherals.

• Memory: memory stores such binary information as instruction, data, provide that information to the microprocessor whenever necessary to execute program the microprocessor reads instruction and data from memory and performs the computing operation in ALU section.

• Input/output:  I/O communicates with the outside world.it is also known as peripherals.

• System bus: it is a communication path between the microprocessor and peripherals. it is nothing a group of wires to carry bits.

ADDRESS BUS:- An address bus is a computer bus 

                               architecture. it is used to transfer data between devices. the devices identified by hardware address of the physical memory(the physical address). the address is stored in the form of binary numbers to enable the data bus to access memory storage.

DATA BUS:-  The data bus in microprocessor is a group of eight 

                         bidirectional lines that are used to transfer 8 bit 

                         data  between the microprocessor and its I/O 

                         memory.

CONTROL BUS:-  A control bus is a part of system bus , used by
                                 CPUs for communicating with other devices within the computer. while  the address bus carries the information about the device with which the CPU is communicating and the data bus carries the actual data being processed, the control bus carries command from the CPU and return status from the devices.


         THE 8085 MICROPROCESSOR UNIT

FEATURES OF 8085 MICROPROCESSOR:-

• Address bus = 16 Bit 
• addressable memory = 2^16 = 64 KB
• data bus                     = 8 BIT

1. It is an 8 bit microprocessor.
2. it operates on a single 5 volt power supply connected at Vcc & the power supply ground is connected through Vss point.
3. it has 16 address lines, hence it can access  64 KB of memory.
4. it operates with 3 Mhz clock frequency.
5. in 8085 MP the lower 8 bit address bus (Ao-A7) & data bus (D0-D7) are multiplex to reduced number of external pins.
6. it supports 74 instructions with following address mode such as

• register addressing mode
• direct addressing mode
• indirect addressing mode
• implied addressing mode

   7. it has 8 bit accumulator , flag register, six 8 bit register  

      (general purpose register = B, C, D, E, H, L) and two 16 bit

      register ( stack pointer and program counter).

   8. it provides 5 hardware interrupt ( TRAP, RST7.5, RST6.5, 

       RST5.5, INTR).

   9. it has seriel input output control unit which allows seriel 

       communiction.

  10. 8085 manufacturer with Nmos technology.

  11. 8085 supports 8 bit address lines for the I/O operations, hence 

        it can access 2^8 = 256 I/O devices.

ADDRESSIBLE  MEMORY:- maximum size of memory that                                                 can be accessed with the given address                                               lines.

  

ARCHITECTURE DIAGRAM OF 8085:-

8085 BUS STRUCTURE:-