MICROPROCESSOR AND INTERFACINGBY: Akshay Makadiya

(( TechByMak ))

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SYLLABUS OF MICROPROCESSOR

Introduction to microprocessor Architecture and block diagram of

microprocessor 8085 microprocesso 8237 DMA Controller 8255 Programmable peripheral interface

device 8254 programmable interval timer 8259 programmable inttrupt controller 8086 microprocessor

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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 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

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MICROPROCESSOR DEF.. CON.. Microprocessor is a programmable device It can be instructed to perform given tasks

with in its capability. 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.

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MICROPROCESSOR DEF.. CON.. Microprocessor is a clock driven

semiconductor device consisting of electronic logic circuits manufactured by using a LSI or VLSI technique.

Microprocessor can be divided into three segments

1)ALU 2)Register array 3)Control unit

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BLOCK DIAGRAM OF MICROPROCESSOR

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INPUT OUTPUT

MEMORY

Microprocessor As

CPU

CHARACTERSTICS WHICH DIFFERENTIATE MICROPROCESSORS Instruction set: The set of instructions that

the microprocessor can execute. 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.

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STRUCTURE OF MICROPROCESSOR

Chip containing no. of elements for the processing purposes.

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HISTORY OF MICROPROCESSOR

Intel's 4004 is considered the first microprocesor .

The 4004 was later followed in 1972 by the 8008, the world's first 8-bit microprocessor.

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HISTORY OF MICROPROCESSOR……

then is the 8080 microprocessor evolved in 1974.

Then comes 8085 that is the 8 bit microprocessor

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CONTINUED… Often the processor is required to manage

various different tasks that have to be scheduled somehow and must also deal with outside 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.

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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 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.

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SOME QUESTIONS

What is SSI,MSI and LSI? What is difference between microprocessor,

microcontroller and microcomputer? What is a bit, byte, nibble and a word? What is difference between compiler and

interpreter? What is instruction and mnemonic?

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8085 PROGRAMMING MODEL

Program counter Stack pointer General purpose registers Accumulator Flag registers Data and address buses

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8085 INSTRUCTION SET

Data transfer operations Arithmetic operations Logical operations Branch operations Machine control operations

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DATA TRANSFER OPERATIONS MOV Rd,Rs MVI R,8 bit HLT 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

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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 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

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ADDRESSING MODE

Immediate addressing mvi Register addressing mov Direct addressing in/out ports Indirect addressing

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LOGICAL OPERATIONS

ANA R ANI 8 bit ORA R ORI 8 bit XRA R XRI 8 bit CMA

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ARTHIMETIC OPERATIONS

ADD R ADI 8 bit SUB R SUI 8 bit INR R DCR R

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BRANCH OPERATIONS

JMP 16 bit 2nd(low) and 3rd(high) byte specifies 16 bit

Memory address JC JNC JZ JNZ JP JM

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MICROPROCESSOR ARCHITECTURE

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

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MICROPROCESSOR ARCHITECTURE

Microprocessor initiated operations Internal operations Externally initiated operations

To perform these functions microprocessor requires a group of logic circuits and set of signals called control signals.

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MICROPROCESSOR INITIATED OPERATIONS Memory read Memory write I/O read I/O write

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INTERNAL OPERATIONS

Store 8-bit data Perform arthimetic and logical operations Test for conditions Sequence the excuetion of operations Store data temporarily during excuetion

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8085 PIN DIAGRAM

Is 8 bit microprocessor, capable of addressing 64k of memory

Has 40 pins ,operate with 3mhz single phase clock

Require +5v of single power supply

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8085 PIN DIAGRAM

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8085 PIN DIAGRAM

Is 8 bit microprocessor, capable of addressing 64k of memory

Has 40 pins ,operate with 3mhz single phase clock

Require +5v of single power supply

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PIN DIAGRAM CONTI….

All the signals are classified into 6 groups Address bus Data bus Control and status signals Power supply and frequency signals Externally initiated signals Serial input output ports

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

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8085 INTERRUPT

What is interrupt? Vectored interrupt Non vectored interrupt Enable and disable interrupt instructions Pending interrupts

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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 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)

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INTERRUPTS

An interrupt is considered to be an emergency signal that may be serviced. 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.

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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 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.

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8085 INTRRUPTS

TRAP RST7.5 RST6.5 RST 5.5 INTR INTA

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INTERRUPT VECTORS AND THE VECTOR TABLE

An interrupt vector is a pointer to where the ISR is stored in memory.

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.

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GENERAL PURPOSE PROGRAMMABLE PERIPHERAL

DEVICES

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

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8255 PROGRAMMABLE PERIPHERAL INTERFACE It can be programmed to transfer data under

various conditions. It has 24 I/O pins. The function of 8255A classified acc to two

modes. A) BSR mode I/O mode

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

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Control Word D7 D6 D5 D4 D3 D2 D1 D0 0/1BSR Mode I/O ModeFor port C Mode0 Mode 1 Mode2No effect on mode Simple I/O Handshake I/O

for ports for ports A and or B

A,B,C

Port C bits

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8254 PROGRAMMABLE INTERVAL TIMER

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8237 DMA CONTROLLER

DMA is an input output technique used for high speed data transfer

Data transfer between system memory and floppy disk

It introduces two new signals that are HOLD HLDA

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DMA CONTROLLER CONT….

DMA Controller consists of DMA channels and interfacing DMA Signals System interface Programming the 8237 DMA Execution consists of Master and slave mode

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8086 MICROPROCESSOR

It is 16 bit microprocessor. Contains 29000 transistors and is fabricated

using HMOS technology. Has addressing capacity of I megabyte. Has 20 address pins. +5v supply voltage

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8086 ARCITECTURE

Internal registers Control logic Instruction queue ALU PSW Pointers Segment registers

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8086 PIN DIAGRAM

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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 contents SI or DI contents and a displacement.The result of such and address computation is called effective address.

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8086 MEMORY SEGMENTATION

Address within segments

Overlapping segments

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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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THANK YOU

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