The document discusses the 8085 microprocessor. It presents information about its features, pin configuration, architecture, registers, bus structure, advantages, and disadvantages. The 8085 is an 8-bit microprocessor with 8 data lines, 16 address lines, and a clock frequency of 3MHz. It has features like 8-bit operations, 64KB memory capacity, and 74 instructions with 5 addressing modes. The document concludes that while the 8085 had benefits like a 5V power supply, it also had limitations like low speed and small memory that led to later versions like the 8086.

1. 12/20/2015

2. Presented by:-
1. Rohan S. Niwal.
2. Shubham Bhaskarvar.
3. Mahima M. Hirapure.
4. Shreya A. Dongre.
5. Sharayu Renghe.
6. Kartik N. Kalpande.
22/20/2015

3. 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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4. 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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5. 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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6. 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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7. 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
then it is working with memory 72/20/2015

8. 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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9. Status Line:-
These are the Output Signal generated by the
microprocessor used to give the status of the
operation perform by the microprocessor. These
are not generally used in small system but can be
used to generate advanced advanced control
signal for the large system
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10. 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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11. 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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12. Architecture of 8085 :-
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13. 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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14. Registers of 8085 (8-bit,16-bit) :-
 (A)Accumulator :-
This is an special purpose register. All the ALU
operations are performed with reference to the
contents of Accumulator.
General Purpose Resistor :-
B,C,D,E,H,L are General purpose registers. These
registers can also used for 16-bit operations in
pairs. The default pairs are BC, DE & HL.
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15. (F)Flag register :-
This register indicates the status of the ALU
operation.
 (PC) Program Counter:-
This is a 16-bit register used to address the
memory location from where an instruction is
going to be executed.
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16. 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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17. The 8085 Bus Structure :-
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18. 2/20/2015 18
Demultiplexing :-

19. Some 8085 Processors Chips :-
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20. 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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21. 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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22. 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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23. 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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