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8085 Microprocessor Architecture Features and working explain

8085 microprocessor is an associate 8-bit microprocessor with a 40 pin inside the microprocessor. The address and information bus are multiplexed between this processor that helps in providing a lot of control signals. 8085 microprocessor has one Non-maskable interrupt and three maskable interrupts.

Introduction of Microprocessor 8085:-

The computer processor that includes the functions of a pc is that the central process one thing unit you on one microcircuit. It largely a couple of integrated circuits the microprocessor as a multi-part may be a clock-driven register-based programmable device that accepts digital information or binary information is input processes it per instruction distort in its memory and supply 3 cents is utilized, microprocessors contain each will national logic and successive digital logic and arithmetic logic unit(ALU). The microprocessor method operates or ranges and easy is portrayed within the binary number or in associate degree 8-bit code. The mixing of the total microprocessor on one the least bit during a few chips greatly reduces the price of process power. 
Integrated circuits processes are created in massive numbers by extremely automatic processes leading to an occasional per-unit value single-chip processors increase responsibility as there are several fewer electrical connections to fail as microprocessor styles get quicker the price of producing a chip with smaller elements depend upon a semiconductor chip identical size typically stays identical before microprocessors it's my computers are enforced use and acts of circuit boards with several medium and little scale integrated circuits microprocessors integrated this anyone or a couple of massive scale x continuing will increase in microprocessor. The capability of the microprocessor has sense rendered alternative styles of pc animals that utterly up Elysee history of computing hardware with the one knowing additional microprocessors.

Microprocessor 8085 Architecture:-

Microprocessor 8085 consists of assorted units and every unit perform its own functions. the assorted units of a microprocessor are listed below

  1. Accumulator
  2. Arithmetic and logic unit(ALU)
  3. General-purpose register 
  4. Program counter
  5. Stack pointer
  6. Temporary register
  7. Flags
  8. Instruction register and Decoder
  9. Timing and control unit
  10. Interrupt control
  11. Serial Input/output control
  12. Address buffer and Address-Data buffer
  13. Address bus and Databus


The accumulator is nothing however a register that will hold 8-bit information. Accumulator aids in storing 2 quantities. the information to be processed by arithmetic and logic unit is hold on within the accumulator. It additionally stores the results of the operation dole out by the Arithmetic and Logic Unit. The accumulator is additionally known as an 8-bit register. The accumulator is connected to the interior Databus and ALU (arithmetic and logic unit). The accumulator may be accustomed to send or receive information from the interior Databus.

Arithmetic and Logic Unit(ALU):-

There is forever a requirement to perform arithmetic operations like +, -, *, / and to perform logical operations like AND, OR, NOT, etc. thus there's a necessity for making a separate unit that will perform such forms of operations. These operations are performed by the Arithmetic and Logic Unit (ALU). ALU performs these operations on 8-bit information. However, these operations can not be performed unless we've got associate degree input (or) information on that the specified operation is to be performed. thus from wherever do, these inputs reach the ALU? For this purpose, the accumulator is employed. ALU gets its Input from the accumulator and temporary register. once process the required operations, the result's hold on the back within the accumulator.

General Purpose Registers:-

Apart from accumulator 8085 consists of six special forms of registers known as General Purpose Registers. These general registers are accustomed to hold information like every different register. The general registers in 8085 processors are B, C, D, E, H, and L. Every register will hold 8-bit information. except for the on top of operating, these registers may be accustomed add pairs to carry 16-bit information. they will add pairs like B-C, D-E, and H-L to store 16-bit information. The H-L tries to work as a memory pointer. A memory pointer holds the address of a specific memory location. They will store 16-bit addresses as they add pairs.

8085-Register Paring Program Counter and Stack Pointer

The program counter may be a special-purpose register. think about that associate degree instruction is being dead by a processor. As presently because the ALU finished corporal punishment the instruction, the processor appearance for consequent instruction to be dead. So, there's a necessity for holding the address of consequent instruction to be dead to save lots of time. This is often taken care of by the program counter.

A program counter stores the address of consequent instruction to be dead. In alternative words, the program counter keeps track of the memory address of the directions that are being dead by the microprocessor and therefore the memory address of consequent instruction that's planning to be dead. Micro increments the program whenever associate degree instruction is being dead so that the program counterpoints to the memory address of consequent instruction that's planning to be dead. The program counter may be a 16-bit register.

Stack Pointer:-

The stack pointer is additionally a 16-bit register that is employed as a memory pointer. A stack is nothing however the portion of RAM (Random access memory). Stack pointer maintains the address of the last computer memory unit that's entered into the stack. Whenever once the information is loaded into a stack, the Stack pointer gets decremented. Conversely, it's incremented once information is retrieved from stack.

Temporary Register:-

As the name suggests this register acts as a brief memory throughout the arithmetic and logical operations. In contrast to alternative registers, this temporary register will solely be accessed by the microprocessor and it's utterly inaccessible to programmers. The temporary register is an associate degree 8-bit register.


Flags are nothing however a bunch of individual Flip-flops. The flags are in the main related to arithmetic and logic operations. The flags can show either a logical (0 or 1) (i.e.) a group or reset betting on the information conditions within the accumulator or numerous alternative registers. A flag is truly a latch that might hold some bits of knowledge. It alerts the processor that some event has taken place.
The potential resolution is from the little flags that are found in the mailboxes in America. The little flag indicates that there's a mailing within the mailbox. Similarly, this denotes that a happening has occurred within the processor.

Intel processors have a group of five flags.

  1. Carry flag
  2. Parity flag
  3. Auxiliary carry flag
  4. Zero flag
  5. Sign flag

Instruction Register and Decoder:-

The instruction register is an 8-bit register rather like each different register of the microprocessor. Think about instruction. The instruction is also something like adding 2 information, moving information, repeating information, etc. Once such associate degree instruction is fetched from memory, it's directed to the Instruction register. Therefore the instruction registers are specifically to store the directions that are fetched from memory.

Timing and Control Unit:-

The temporal arrangement and control unit may be an important unit because it synchronizes the registers and flow of knowledge through numerous registers and different units. This unit consists of associate degree generator and controller sequencer that sends control signals required for internal and external control of knowledge and different units.

The generator generates two-phase clock signals that aid in synchronizing all the registers of 8085 microprocessor.

Signals that are related to the timing and control unit are:

  1. Control Signals: ready, RD’, WR’, ALE
  2. Status Signals: S0, S1, IO/M’
  3. DMA Signals: HOLD, HLDA

Interrupt control

As the name suggests this control interrupts a method. Think that a microprocessor is execution the most program. Now whenever the interrupt signal is enabled or requested the microprocessor shifts the management from the most program to method the incoming request and once the completion of the request, the management goes back to the most program. As an example, an associate degree Input/output device might send an interrupt signal to advise that the information is prepared for input. The microprocessor briefly stops the execution of the most program and transfers management to the input and output device. Once aggregation the input file the control is transferred back to the most program.
Interrupt signals present in 8085 are: INTR, RST 7.5, RST 6.5, RST 5.5, entice these four interrupts entice may be NON-MASKABLE interrupt management and alternative 3 are maskable interrupts. A non-maskable interrupt is an interrupt that is given the very best priority within the order of interrupts. Suppose you wish an instruction to be processed straight away, then you'll offer the instruction as a non-maskable interrupt. More the non-maskable interrupt can not be disabled by computer programmers at any purpose of your time. Whereas the maskable interrupts may be disabled and enabled victimization EI and DI directions. Among the maskable interrupts, RST seven.5 is given the very best priority on top of RST six.5 and the least priority is given to INTR.

Serial Input and output control
The input and output of serial information may be allotted exploitation in two directions in 8085.

  1. SID-Serial input data
  2. SOD-Serial Output data

Two additional directions are accustomed to performing serial-parallel conversion required for serial input and output(I/O) devices.

  1. SIM
  2. RIM

Address buffer and Address-Data buffer

The contents of the stack pointer and program counter are loaded into the address buffer and address-data buffer. These buffers are then accustomed to driving the external address bus and address-data bus. Because of the memory and I/O chips are connected to those buses, the processor will exchange desired information to the memory and input and output chips. The address-data buffer isn't solely connected to the external information bus however additionally to the inner information bus that consists of 8-bits. The address information buffer will each send and receive information from the inner information bus.

Address bus and Databus:

We know that 8085 is an associate degree 8-bit microprocessor. Therefore the information bus gift within the microprocessor is additionally 8-bits wide. Thus 8-bits of knowledge may be transmitted from or to the microprocessor. However, the 8085 microprocessor needs a 16-bit address bus because the memory addresses are 16-bit wide. The 8 important bits of the address are transmitted with the assistance of address bus and therefore the eight least significant bits are transmitted with the assistance of a multiplexed address/data bus. The eight-bit information bus is multiplexed with the eight least vital bits of the address bus. The address bus and data bus are time-multiplexed. This suggests for few microseconds, the eight least vital bits of the address are generated, whereas for the following few seconds a similar pin generates the information. This is often known as Time multiplexing. However, there are things wherever there's a requirement to transmit each information and addresses at the same time. For this purpose, a symptom known as an ale (address latch enable) is employed. ALU signal holds the obtained address in its latch for an extended time till the information is obtained so once the microprocessor sends the information next time the address is additionally obtainable at the output latch. This system is named Address/Data demultiplexing.

Know About What are the Definition and basic introduction of Microprocessor and microcontroller and differences between the Microprocessor and Microcontroller?

1 comment:

  1. Điều này góp phần bảo vệ sức khỏe cho
    gia đình bạn.


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