An Introduction to Microprocessor 8085


An Introduction to Microprocessor 8085

An Introduction to Microprocessor 8085
An Introduction to Microprocessor 8085


    Microprocessor is a digital device on a chip which can fetch instructions from a memory, decode and execute them i.e. performs certain arithmetic and logical operations, accept data from input device, and send results to output devices. Therefore, a microprocessor interfaced with memory and Input/ Output devices forms a Microcomputer.

There are five building blocks of a digital computer:

Input Unit

    Through this unit data and instructions are fed to the memory of the computer. The basic purpose of this unit is to read the data into the machine. The program from the memory is read into the machine along with the input data which are required to solve or compute the problem by the machine. The typical devices which are used for this purpose are keyboards, paper tape reader and toggle switches.

Memory Unit 

    The memory unit of a digital computer consists of devices which are capable of storing information. The memory of a computer is used for storing two distinct type of information such as data to be processed by the computer and program through which the result of the desired problem is obtained. Computer program and data are stored in the Memory Unit. This usually consists of chips of both ROMs (Read Only Memories) and RAMs (Random Access Memories) either bipolar or MOS.


Arithmetic and Logical Unit 

    This unit is used for performing arithmetic operations such as Addition, Subtraction, Multiplications, division and other logical (ALU) operations on the data. The control unit guides ALU which of the operations are to be performed. The sequence of the instructions is controlled by the control unit.

Control Unit 

    The control unit performs the most important function in a computer. It controls all other units and also controls the flow of data from one unit to another for performing computations. It also sequences the operations. It instructs all the units to perform the task in a particular sequence with the help of clock pulses.

Output Unit 

    After processing of the data in the Arithmetic and Logical Unit, the results are displayed to the output world through this unit. The CRTs (Cathode Ray Tubes), LEDs (Light Emitting Diodes) and Printer.

Introduction & application of 8051 Microcontroller


Table of content 

Chapter 1 Evolution and History of Microprocessors

1.1 Introduction

1.2 Evolution/History of Microprocessors

1.3 Basic Microprocessor System

1.4 Brief Description of 8-Bit Microprocessor 8080A

1.5 Computer Programming Languages

Chapter 2 SAP – I

2.1 Architecture of SAP – I

2.2 Instruction Set of SAP-I Computer

2.3 Programming of SAP-I Computer

2.4 Working of SAP-I Computer

2.5 Hardware Design of SAP-I Computer

Chapter 3 SAP – II

3.1 Architecture of SAP-II Computer

3.2 Instruction Set of SAP-II Computers

3.3 Machine Cycle and Instruction Cycle

3.4 Addressing Modes

3.5 Instruction Types

3.6 Flags

3.7 Assembly Language Programming

3.8 Delay Calculations

Chapter 4 SAP – III

4.1 Programming Model of SAP-III Computer

4.2 Instruction Set of SAP-III Computer

4.3 Time Delay Introduced by a Register Pair

Chapter 5 The 8085 Microprocessor

5.1 Architecture of 8085 Microprocessor

5.2 Pin Description of 8085

5.3 Instruction Set of 8085 Microprocessor

5.4 Timing Diagram for 8085 Instructions

Chapter 6 Programming of 8085

6.1 Simple Progams

6.2 Progams on code conversion

6.3 Progams on addition and subtraction

6.4 Progams to find largest or smallest number

6.5 Progams to arrange a given series in ascending or descending order

6.6 Program on Multiplication

6.7 Program on 8-Bit Division

6.8 Miscellaneous Programs

Chapter 7 Interrupt Instructions of 8085

7.1 Methods of I/O Operations

7.2 Data Transfer Schemes

7.3 The 8085 Interrupts

7.4 Software Interrupts

7.5 Hardware Interrupts

7.6 Interrupt Control Circuit

7.7 Interrupt Instructions

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