1. techbymak
MICROPROCESSOR AND
INTERFACING
BY: Akshay Makadiya
(( TechByMak ))

2. SYLLABUS OF MICROPROCESSOR
 Introduction to microprocessor
 Architecture and block diagram of
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microprocessor
 8085 microprocesso
 8237 DMA Controller
 8255 Programmable peripheral interface device
 8254 programmable interval timer
 8259 programmable inttrupt controller
 8086 microprocessor

3. WHAT IS MICROPROCESSOR?
A silicon chip that contains a CPU. In the world of
personal computers, the terms microprocessor
and CPU are used interchangeably. At the heart
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of all personal computers and most workstations
sits a microprocessor. Microprocessors also
control the logic of almost all digital devices, from
clock radios to fuel-injection systems for
automobiles

4. MICROPROCESSOR DEF.. CON..
 Microprocessor is a programmable device
 It can be instructed to perform given tasks with
in its capability.
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 The programmer selects instruction from the list
and determines the sequence of execution for a
given task.
 It takes input from the input device and process
the input as it behaves like a CPU and gives the
output.

5. MICROPROCESSOR DEF.. CON..
 Microprocessor is a clock driven semiconductor
device consisting of electronic logic circuits
manufactured by using a LSI or VLSI technique.
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 Microprocessor can be divided into three
segments
 1)ALU
 2)Register array
 3)Control unit

6. BLOCK DIAGRAM OF
MICROPROCESSOR
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Microprocessor
INPUT As OUTPUT
CPU
MEMORY

7. CHARACTERSTICS WHICH
DIFFERENTIATE
MICROPROCESSORS
 Instruction set: The set of instructions that the
microprocessor can execute.
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 bandwidth : The number of bits processed in a
single instruction.
 clock speed : Given in megahertz (MHz), the
clock speed determines how many instructions
per second the processor can execute.

8. STRUCTURE OF MICROPROCESSOR
 Chip containing no. of elements for the
processing purposes.
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9. HISTORY OF MICROPROCESSOR
 Intel's 4004 is considered the first microprocesor .
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 The 4004 was later followed in 1972 by the 8008,
the world's first 8-bit microprocessor.

10. HISTORY OF MICROPROCESSOR……
 then is the 8080 microprocessor evolved in 1974.
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 Then comes 8085 that is the 8 bit microprocessor

11. CONTINUED…
 Often the processor is required to manage
various different tasks that have to be scheduled
somehow and must also deal with outside
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interrupt sources such as an alarm when
something goes wrong.
 Real-time systems are those in which timeliness
is as important as the correctness of the outputs,
although this does NOT mean that they have to
be ?fast systems?.
 A real-time system does not have to process data in
microseconds to be considered real-time - it must simply
have response times that are constrained and thus
predictable.

12. REAL LIFE APPLICATIONS OF
MICROPROCESSOR
 Microprocessors are used to handle a set of tasks that
control one or more external events or systems.
 Microprocessors are typically used in either reactive or
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embedded systems.
 Reactive systems are those that have an ongoing interaction
with their environment - for example, a fire-control system
that constantly reacts to buttons pressed by a pilot.
 Embedded systems are those used to control specialized
hardware in which the computer system is installed - for
example, the microprocessor system used to control the
fuel/air mixture in the carburetor of many automobiles.
 In embedded systems the software system is completely
encapsulated by the hardware that it controls.

13. SOME QUESTIONS
 What is SSI,MSI and LSI?
 What is difference between microprocessor,
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microcontroller and microcomputer?
 What is a bit, byte, nibble and a word?
 What is difference between compiler and
interpreter?
 What is instruction and mnemonic?

14. 8085 PROGRAMMING MODEL
 Program counter
 Stack pointer
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 General purpose registers
 Accumulator
 Flag registers
 Data and address buses

15. 8085 INSTRUCTION SET
 Data transfer operations
 Arithmetic operations
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 Logical operations
 Branch operations
 Machine control operations

16. DATA TRANSFER OPERATIONS
 MOV Rd,Rs
 MVI R,8 bit
 HLT
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 IN 8 bit port address accept the data from the
input port specified in the second byte and loads
into the accumulator.
 NOP
 OUT 8 bit port address copies the contents of
the accumulator to the output port specified in
the second byte,2 byte instruction

17. DATA TRANSFER OPERATIONS
 This group of instructions copies data from a
location called a source to another a location
called destination without modifying the contents
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of the source.
 Data transfer can be between 1)registers
 Specified data byte to a register or memory
location
 Between a memory location and a register

18. ADDRESSING MODE
 Immediate addressing mvi
 Register addressing mov
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 Direct addressing in/out ports
 Indirect addressing

19. LOGICAL OPERATIONS
 ANA R
 ANI 8 bit
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 ORA R
 ORI 8 bit
 XRA R
 XRI 8 bit
 CMA

20. ARTHIMETIC OPERATIONS
 ADD R
 ADI 8 bit
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 SUB R
 SUI 8 bit
 INR R
 DCR R

21. BRANCH OPERATIONS
 JMP 16 bit 2nd(low) and 3rd(high) byte specifies 16 bit
 Memory address
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 JC
 JNC
 JZ
 JNZ
 JP
 JM

22. MICROPROCESSOR ARCHITECTURE
 The process of data manipulation and
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communication is determined by the logic design
of the microprocessor called the arcitecture.

23. MICROPROCESSOR
ARCHITECTURE
 Microprocessor initiated operations
 Internal operations
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Externally initiated operations
To perform these functions microprocessor requires
a group of logic circuits and set of signals called
control signals.

24. MICROPROCESSOR INITIATED
OPERATIONS
 Memory read
 Memory write
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 I/O read
 I/O write

25. INTERNAL OPERATIONS
 Store 8-bit data
 Perform arthimetic and logical operations
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 Test for conditions
 Sequence the excuetion of operations
 Store data temporarily during excuetion

26. 8085 PIN DIAGRAM
Is 8 bit microprocessor, capable of addressing 64k
of memory
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Has 40 pins ,operate with 3mhz single phase clock
Require +5v of single power supply

27. 8085 PIN DIAGRAM
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28. 8085 PIN DIAGRAM
Is 8 bit microprocessor, capable of addressing 64k
of memory
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Has 40 pins ,operate with 3mhz single phase clock
Require +5v of single power supply

29. PIN DIAGRAM CONTI….
 All the signals are classified into 6 groups
 Address bus
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 Data bus
 Control and status signals
 Power supply and frequency signals
 Externally initiated signals
 Serial input output ports

30. BLOCK DIAGRAM OF 8085
MICROPROCESSOR
 It includes
 Arithmetic and logic unit
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 Timing and control unit
 Instruction register and decoder
 Register array
 Interrupt control
 Serial input output control

31. 8085 INTERRUPT
 What is interrupt?
 Vectored interrupt
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 Non vectored interrupt
 Enable and disable interrupt instructions
 Pending interrupts

32. 8085 INTERRUPT
 Interrupt is a process where an external device can get the
attention of the microprocessor.
 The process starts from the I/O device
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 The process is asynchronous.
 Classification of Interrupts
 Interrupts can be classified into two types:
 Maskable Interrupts (Can be delayed or Rejected)
 Non-Maskable Interrupts (Can not be delayed or Rejected)
 Interrupts can also be classified into:
 Vectored (the address of the service routine is hard-wired)
 Non-vectored (the address of the service routine needs to be supplied
externally by the device)

33. INTERRUPTS
 An interrupt is considered to be an emergency
signal that may be serviced.
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 The Microprocessor may respond to it as soon as
possible.
 What happens when MP is interrupted ?
 When the Microprocessor receives an interrupt signal, it
suspends the currently executing program and jumps to
an Interrupt Service Routine (ISR) to respond to the
incoming interrupt.
 Each interrupt will most probably have its own ISR.

34. INTERRUPTS
 When a device interrupts, it actually wants the
MP to give a service which is equivalent to
asking the MP to call a subroutine. This
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subroutine is called ISR (Interrupt Service
Routine)
 The ‘EI’ instruction is a one byte instruction and
is used to Enable the non-maskable interrupts.
 The ‘DI’ instruction is a one byte instruction and
is used to Disable the non-maskable interrupts.
 The 8085 has a single Non-Maskable interrupt.
 The non-maskable interrupt is not affected by the value
of the Interrupt Enable flip flop.

35. 8085 INTRRUPTS
 TRAP
 RST7.5
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 RST6.5
 RST 5.5
 INTR
 INTA

36. INTERRUPT VECTORS AND THE
VECTOR TABLE
 An interrupt vector is a pointer to where the ISR
is stored in memory.
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 All interrupts (vectored or otherwise) are mapped
onto a memory area called the Interrupt Vector
Table (IVT).
 The IVT is usually located in memory page 00
(0000H - 00FFH).
 The purpose of the IVT is to hold the vectors that
redirect the microprocessor to the right place when
an interrupt arrives.

37.  GENERAL
PURPOSE
PROGRAMMABLE PERIPHERAL
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DEVICES

38.  8255A Programmable peripheral interface
 8254 programmable interval timer
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 8259 Programmable interval timer
 8237 DMA Controller

39. 8255 PROGRAMMABLE
PERIPHERAL INTERFACE
 It can be programmed to transfer data under
various conditions.
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 It has 24 I/O pins.
 The function of 8255A classified acc to two
modes.
 A) BSR mode
 I/O mode

40. 8255 PROGRAMMABLE
PERIPHERAL INTERFACE
 Block diagram of 8255A
 Control word
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 BSR mode
 Mode 0
 Mode 1
 Mode 2

41. Control Word

 D7 D6 D5 D4 D3 D2 D1 D0
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0/1
BSR Mode I/O Mode
For port C Mode0 Mode 1 Mode2
No effect on mode Simple I/O Handshake I/O
for ports for ports A and or B
A,B,C
 Port C bits

42. 8254 PROGRAMMABLE INTERVAL
TIMER
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43. 8237 DMA CONTROLLER
 DMA is an input output technique used for high
speed data transfer
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 Data transfer between system memory and
floppy disk
 It introduces two new signals that are
 HOLD
 HLDA

44. DMA CONTROLLER CONT….
 DMA Controller consists of
 DMA channels and interfacing
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 DMA Signals
 System interface
 Programming the 8237
 DMA Execution consists of
 Master and slave mode

45. 8086 MICROPROCESSOR
 It is 16 bit microprocessor.
 Contains 29000 transistors and is fabricated
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using HMOS technology.
 Has addressing capacity of I megabyte.
 Has 20 address pins.
 +5v supply voltage

46. 8086 ARCITECTURE
 Internal registers
 Control logic
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 Instruction queue
 ALU
 PSW
 Pointers
 Segment registers

47. 8086 PIN DIAGRAM
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48. 8086 EFFECTIVE ADDRESS
COMPUTATIONS
 To provide flexible base addressing and indexing
a data address may be formed by addressing
together a combination of the BX or BP register
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contents SI or DI contents and a
displacement.The result of such and address
computation is called effective address.

49. 8086 MEMORY SEGMENTATION
 Address within segments
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 Overlapping segments

50. PROGRAM RELOCATION USING
CS REGISTER
 If a programmer wants to relocate the program
by any means ,he can relocate the program using
cs register.
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