an introduction to microprocessor 8085

535 Pages·2016·3.91 MB·English

AN INTRODUCTION TO MICROPROCESSOR 8085
By
Dr. D. K. Kaushik
Principal, Manohar Memorial (P.G.) College,
Fatehabad (Haryana) India
Dhanpat Rai Publishing co., New Delhi
AN INTRODUCTION TO MICROPROCESSOR 8085

Chapter 1 Evolution and History of Microprocessors
1.1 Introduction
1.2 Evolution/History of Microprocessors
1.3 Basic Microprocessor System
1.3.1 Address Bus
1.3.2 Data Bus
1.3.3 Control Bus
1.4 Brief Description of 8-Bit Microprocessor 8080A
1.5 Computer Programming Languages
1.5.1 Low-Level Programming Language
1.5.2 High-Level Programming Language
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
2.4.1 Fetch Cycle
2.4.2 Execution Cycle
2.5 Hardware Design of SAP-I Computer
2.5.1 Design of Program Counter
2.5.2 Memory Unit
2.5.3 Instruction Register
2.5.4 Controller-Sequencer
2.5.5 Accumulator
2.5.6 Adder-Subtractor
2.5.7 B-Register
2.5.8 Output Register
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
4.2.1 Data Transfer Group
4.2.2 Arithmetic Group of Instructions
4.2.3 Logic Transfer Group
4.2.4 Branch Group
4.2.5 Stack and Input / Output Instructions
4.3 Time Delay Introduced by a Register Pair
Chapter 5 The 8085 Microprocessor
5.1 Architecture of 8085 Microprocessor
5.1.1 Register Section
5.1.2 Address Buffer and Address-Data Buffer
5.1.3 Arithmetic and Logical Unit (ALU)
5.1.4 Timing and Control Unit
5.1.5 Interrupt Control
5.2 Pin Description of 8085
5.3 Instruction Set of 8085 Microprocessor
5.4 Timing Diagram for 8085 Instructions
5.4.1 Timing Diagram of MOV reg, M
5.4.2 Timing Diagram of MOV M, reg
5.4.3 Timing Diagram of MVI reg, data
5.4.4 Timing Diagram of MOV reg2, reg1
5.4.5 Timing Diagram of MVI M, data
5.4.6 Timing Diagram of XCHG
5.4.7 Timing Diagram of LXI rp, dbyte

5.4.8 Timing Diagram of IN byte
Chapter 6 Programming of 8085
6.1 Simple Progams
6.2 Progams on code conversion
6.2.1 BCD to Binary Conversion
6.2.2 Binary to BCD (Unpacked) Conversion
6.2.3 Binary to ASCII Conversion
6.2.4 ASCII to Binary 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
7.1.1 Memory Mapped I/O
7.1.2 I/O Mapped I/O or Isolated I/O
7.2 Data Transfer Schemes
7.2.1 Programmed I/O Data Transfer
7.2.2 Interrupt Driven I/O Data Transfer
7.2.3 Direct Memory Access (DMA) Data Transfer
7.3 The 8085 Interrupts
7.4 Software Interrupts
7.5 Hardware Interrupts
7.6 Interrupt Control Circuit
7.7 Interrupt Instructions
7.8 Serial Input and Output Data Transfer
Chapter 8 Programmable Peripheral Interface (PPI) 8255A
8.1 Details of PPI IC 8255A
8.2 Operational Modes of 8255A
8.3 Control Word Format for 8255A
8.4 Programming in Mode 0
8.5 Programming in Mode 1 (strobed Input/Output)
8.5.1 Input Control Signals in Mode 1
8.5.2 Output Control Signals in Mode 1
8.6 Programming in Mode 2 (Strobed Bidrectional Bus I/O)
8.7 Bit Set/Reset (BSR) Mode
Chapter 9 Programmable Interval Timer/Counter: 8253
9.1 INTEL Programmable Interval Timer 8253
9.2 Block Diagram of 8253
9.3 Logics for Counters
9.4 Control Word Format of 8253
9.5 Interfacing and programming of 8253
9.6 Programming of 8253 in Mode 0: Interrupt on Terminal Count
9.7 Programming of 8253 in Mode 1: Programmable One Shot
9.8 Programming of 8253 in Mode 2: Rate Generator
9.9 Programming of 8253 in mode 3: Square Wave Generator
9.10 Programming of 8253 in mode 4: Software Triggered Strobe
Chapter 10 Programmable Keyboard and Display Interface: 8279
10.1 INTEL Programmable Keyboard/Display Interface 8279
10.2 Block Diagram of 8279
10.3 Functional Description of 8279
10.4 Key Board San
10.5 Scanned Keyboard
10.5.1 Two-key Lockout
10.5.2 N-key Rollover
10.6 Scanned Sensor Matrix
10.7 Strobed Input
10.8 Display Interface
10.9 Display Modes
10.9.1 Left Entry Mode (Type Writer Mode)
10.9.2 Right Entry Mode (Calculator Mode)
10.10 Programming of 8279
10.10.1 Keybaord/Display Mode Set
10.10.2 Program Clock
10.10.3 Read FIFO/Sensor RAM
10.10.4 Read Display RAM
10.10.5 Write Display RAM
10.10.6 Display Write Inhibit/Blanking
10.10.7 Clear
10.10.8 End Interrupt/Error Mode Set
10.11 Status Register (IN Operation)
10.12 Interfacing of 8279 with 8085
Chapter 11 Programmable Interrupt Controller: 8259
11.1 Programmable Interrupt Controller 8259
11.2 Block Diagram of 8259
11.3 Interfacing of 8259A with 8085A
11.4 Vectoring Data Formats for 8259
11.5 Initialization of 8259
11.6 Initialization Command Words (ICWs)
11.7 Operation Command Words (OCWs)
11.8 Interrupt Modes of 8259A
11.8.1 Fully Nested Mode (FNM)
11.8.2 Rotating Priority Mode
11.8.3 Special Mask Mode
11.8.4 Polled Mode

11.9 Status Read Operation of 8259
Chapter 12 Direct Memory Access Controller: 8257
12.1 Block Diagram of 8257
12.1.1 DMA Channels
12.1.2 Data Bus Buffer
12.1.3 Read/ Write Logic
12.1.4 Control Logic
12.1.5 Mode Set Register
12.1.6 Status Word Register
12.2 Programming of 8257

12.3 DMA Interfacing Circuit
Chapter 13 Interfacing Data converters: A/D and D/A Converters
13.1 Digital to Analog Converter
13.1.1 Resistive Divider D/A converter
13.1.2 Binary Ladder D/A Converter
13.2 Performance Criteria for D/A Converter
13.3 D/A Converter IC 0808
13.4 Interfacing of D/A Converter
13.5 Microprocessor Compatible D/A Converter
13.6 Analog to Digital Converter
13.7 Simultaneous A/D Converter
13.8 Successive Approximation A/D Converter
13.9 Counter or Digital Ramp Type A/D Converter
13.10 Single Slope A/D Converter
13.11 Dual Slope A/D Converter
13.12 ADC 0808/0809
13.13 A/D Converter Using D/A Converter and Software
Chapter 14 Serial Communication and Programmable Communication
Interface
14.1 Serial Data Communication
14.2 Modem
14.3 Serial Communication Standard
14.4 Asynchronous Software Approach
14.5 Programmable Communication Interface
14.6 Block Diagram of 8251A
14.6.1 Read/Write Control Logic
14.6.2 Transmitter Section
14.6.3 Receiver Section
14.6.4 Modem Control
14.7 Interfacing of 8251A
14.8 Programming of 8251A
14.8.1 Initialization of 8251A in Asynchronous Mode
14.8.2 Initialization of 8251A in Synchronous Mode
Chapter 15 Applications of Microprocessor
15.1 Real Time Clock with On/Off Timer
15.2 Microprocessor Based LED Dial Clock
15.3 Design of Microprocessor Based Running light
15.4 Microprocessor Based Automatic School bell system
15.5 Microprocessor Based Traffic Light
15.5.1 Another Design of Microprocessor Based Traffic Light
15.6 Microprocessor Based Stepper Motor Control
15.7 Microprocessor Based Washing Machine Controller
15.8 Microprocessor Based Water Level Controller
15.9 Microprocessor Based Temperature Controller

Appendices
1
Evolution and History of
Microprocessors

To understand the working and programming of microprocessors, it is very
necessary to know the details of evolution and history of microprocessors which will be
discussed in this chapter. In the succeeding chapters of this book, the detailed discussion
on the basics of microprocessors will be made. For the beginners it is very difficult to
understand the operation of a digital computer as it contains large details, so efforts have
been made to envisage the operation of a digital computer in step by step manner.

1.1 INTRODUCTION

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. Basically, there are five building blocks of a digital computer namely:

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 etc.

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 This unit is used for performing arithmetic operations such as
Logical Unit 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 etc.
form the output unit.

In a computer system ALU and Control Unit are combined in one unit called
Central Processing Unit (CPU). The block diagram of a computer is shown in figure 1.1.

Fig. 1.1
2