12/20/2015

Presented by:-1. Rohan S. Niwal.

2. Shubham Bhaskarvar.

3. Mahima M. Hirapure.

4. Shreya A. Dongre.

5. Sharayu Renghe.

6. Kartik N. Kalpande.

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Introduction :- Microprocessor is a programmable electronic device

which is used in small system such as pocket

calculator , digital watches and mostly in the

Smartphone's.

The most of microprocessor comes in 1970 and where

is used in the calculator.

The 8085 is an 8 bit microprocessor. It having 8 bit of

data bus and 16 bit of address bus.

The 8085 microprocessor required only the 3MHz

clock Frequency . It having 64 KB of memory.

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Features :-8 bit microprocessor(8085 microprocessor can read or

write or perform arithmetic and logical operations on 8-bit

data at time)

It has 8 data lines and 16 address lines hence capacity is

216 = 64 KB of Memory.

Cock frequency is 3 MHz

It requires +5V power supply.

It is a single chip NMOS device implemented with 6200

transistors.

It provides 74 instructions with five addressing modes.

It provides 5 hardware interrupt and 8 software interrupts.

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Pin Configuration:-

40 pins classified into 6 groups:

Data bus.

2.Control & status lines.

3.Externally generated .

4.Serial interface .

5.Power supply & clock.

6.Address bus

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Pin Configuration Cont…

1) Address Bus (A15-A8 and AD7-AD0):-

The microprocessor 8085 has 16 bit

address lines from A15-A8 and AD7-AD0. These

lines are used to transfer 16 bit address of

memory as well as 8-bit address of I/O ports.

2) Data Bus:-

The lower 8 lines (AD7-AD0) are often

called as multiplexed data lines.

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Control lines :-

RD :- RD is read as Read operation. This is active low

signal which indicates that the selected I/O or memory

device is to be read and also is available on the data

bus.

WR :-WR is read as Write operation. This is active low

signal which indicates that the data on data bus are to be

written into a selected memory location.

IO/ M:-It is use to indicate that whether microprocessor is

working with input/ output devices or with memory. if it is

active high it works with I/O device. And if it is active low

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Status lines : -

8

IO/M S1 S2 Machine Cycle

0 0 1 Memory Write

0 1 0 Memory Read

0 1 1 OP- Code Latch

1 0 1 IO Write

1 0 0 IO Read

1 1 1 No Operation

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Status Line:-These are the Output Signal generated by the

microprocessor used to give the status of theoperation perform by the microprocessor. Theseare not generally used in small system but can beused to generate advanced advanced controlsignal for the large system

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Special signal :-ALE (Address Latch Enable):

The ALE signal is used to enable or disable the external

latch IC (74373/8212).

The external latch IC is used for the de-multiplexing

of AD7-AD0 lines, i.e., it is used to separate the

address and data from AD7-AD0 lines.

If ALE = 1/0 then external latch IC is enabled/disabled

respectively.

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Intrupt control group:- Intrupt is use to control intrupt related issue with the

microprocessor if user want to use intrupt service.

Here the intrupt serice means the extra service want by the use the user.

INTR means Intrupt request,it is use for this extra service.

It is active high input signal.

And the response of giving the extra service to the user or not is shown by the microprossesor using INTA.

INTA means Intrupt acknowlegment.

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Architecture of 8085 :-

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Architecture 0f 8085Cont…

1 ALU.

2. Timing and Control Unit.

3. General Purpose Registers.

4. Program Status word.

5. Program Counter.

6. Stack Pointer.

7. Instruction Register and

Instruction Decoder.

8. Interrupt Control.

9.Serial I/O Control.

10.Address Bus.

11. Data Bus.

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Registers of 8085 (8-bit,16-bit) :-

(A)Accumulator :-

This is an special purpose register. All the ALUoperations are performed with reference to thecontents of Accumulator.

General Purpose Resistor :-

B,C,D,E,H,L are General purpose registers. Theseregisters can also used for 16-bit operations inpairs. The default pairs are BC, DE & HL.

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(F)Flag register :-

This register indicates the status of the ALUoperation.

(PC) Program Counter:-

This is a 16-bit register used to address thememory location from where an instruction isgoing to be executed.

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ALU –Arithmetic & Logic Unit :-ALU of 8085 performs 8-bit arithmetic & logical

operations. The operations are generally performed with Accumulator as one of the operands. The result is saved in accumulator register.

Timing & Control Unit :-This unit works as the brain of the CPU and generates

all the timing and control signals to perform all the internal & external operations of the CPU.

Instruction Decoder & Machine Cycle Encoder Unit :-

This unit decodes the op-code stored in the Instruction Register (IR) and encodes it for the timing & control unit to perform the execution of the instruction.

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The 8085 Bus Structure :-

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Demultiplexing :-

Some 8085 Processors Chips :-

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Advantages of 8085 :- It required only +5v Power Supply.

It does not required any special or external clock

generator.

It has 5 addressing mode.

There are 8 software interrupts in 8085 microprocessor.

In respond to INTR signal 8085 generates the three

different acknowledgement signal (i.e. INTA).

It have 5 Hardware interrupts .

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Disadvantages of 8085 :- It does not Support Memory Segmentation.

It does not supports Pipeline.

Instruction Queue is not presents in 8085.

It can handle in only one (1) mode.

It has less memory only 64 KB.

Only 8-bit data operation can perform.

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Conclusion :-1. Due to this microprocessor somewhere the work of

workers get less.

2. But the size of the microprocessor is not sufficient.

3. This 8085 has low speed .

4. It has no future scope.

5. And to solve this problem the later version of 8085 came to know as 8086.

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Reference by:-1. www.google.com

2. www.yahoo.com

3. www.ask.com

4. Tech max book .

5. Nirali book.

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