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Microprocessor based System DesignRavi S Gupta

Organization Goals of the Course Historical Perspective - Microprocessors The Technology Aspect: Moores Law Inside a Microprocessor Processor system architecture Computer Classification Advantages of Microprocessor based system design Disadvantages of Microprocessor based system design Microcontroller Digital Signal Processor Functional and Architecture description of 8085 Pin description of 8085 Memory Interfacing Addressing Modes in 8085 Instruction Set of 8085 Interrupts of 8085 Timing Diagram of 8085

Goals and ObjectivesIn this course, you will: Learn how the hardware (HW) and software (SW) components of a microprocessor-based system work together to implement digital systems. Learn both HW and SW aspects of integrating digital devices (memory, I/O interfaces, etc.) into microprocessor systems. Get practical hands-on experience in system design and assembly language programming.

Goals and ObjectivesIn the classroom lectures, you will learn more about the hardware architecture aspects of microprocessors, their internal building blocks, operation principles, interfacing with other digital systems etc

In the laboratory sessions, you will learn more about the machine code and assembly language programming of microprocessors, and implementation of digital systems using these devices.

Microprocessors are found almost everywhere

Microprocessor HistoryA microprocessor -- also known as a CPU or central processing unit -- is a complete computation engine that is fabricated on a single chip. The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very powerful -- all it could do was add and subtract, and it could only do that 4 bits at a time. But it was amazing that everything was on one chip. Prior to the 4004, engineers built computers either from collections of chips or from discrete components (transistors). The 4004 powered one of the first portable electronic calculators.

The first microprocessor to make it into a home computer was the Intel 8080, a complete 8-bit computer on one chip, introduced in 1974. The first microprocessor to make a real splash in the market was the Intel 8088, introduced in 1979 and incorporated into the IBM PC (which first appeared around 1982). If you are familiar with the PC market and its history, you know that the PC market moved from the 8088 to the 80286 to the 80386 to the 80486 to the Pentium to the Pentium II to the Pentium III to the Pentium 4. All of these microprocessors are made by Intel and all of them are improvements on the basic design of the 8088. The Pentium 4 can execute any piece of code that ran on the original 8088, but it does it about 5,000 times faster!

Historical PerspectiveN am e 8 08 0 8 08 8 8 0 28 6 8 0 38 6 8 0 48 6 P en tium Da te Tran sisto rs M ic rons 19 74 19 79 19 82 19 85 19 89 19 93 6 ,00 0 2 9 ,0 00 13 4 ,0 00 27 5 ,0 00 1 ,20 0,0 0 0 3 ,10 0,0 0 0 6 3 1 .5 1 .5 1 0 .8 Cloc k s pe ed 2 MH z 5 MH z 6 MH z 16 MHz 25 MHz 60 MHz Da ta w idth 8 bits 1 6 b its 8 -b it b us 1 6 b its 3 2 b its 3 2 b its 3 2 b its 6 4 -b it bu s 3 2 b its 6 4 -b it bu s 3 2 b its 6 4 -b it bu s 3 2 b its 6 4 -b it bu s M IPS 0.6 4 0.3 3 1 5 20 1 00

P en tium II P en tium III P en tium 4

19 97

7 ,50 0,0 0 0

0 .35

23 3 M Hz

~ 3 00

19 99

9 ,50 0,0 0 0

0 .25

45 0 M Hz

~ 5 10

20 00 4 2 ,0 0 0,0 00

0 .18

1 .5 G Hz

~1 ,70 0

The date is the year that the processor was first introduced. Transistors is the number of transistors on the chip. You can see that the number of transistors on a single chip has risen steadily over the years. Microns is the width, in microns, of the smallest wire on the chip. For comparison, a human hair is 100 microns thick. As the feature size on the chip goes down, the number of transistors rises. Clock speed is the maximum rate that the chip can be clocked at. Data Width is the width of the ALU. An 8-bit ALU can add/subtract/multiply/etc. two 8-bit numbers, while a 32-bit ALU can manipulate 32bit numbers. MIPS stands for "millions of instructions per second" and is a rough measure of the performance of a CPU.

Inside a Microprocessor The microprocessor is a semiconductor device (Integrated Circuit) manufactured by the VLSI (Very Large Scale Integration) technique. It includes the ALU, register arrays and control circuit on a single chip. To perform a function or useful task we have to form a system by using microprocessor as a CPU and interfacing memory, input and output devices to it. A system designed using a microprocessor as its CPU is called a microcomputer. The Microprocessor based system (single board microcomputer) consists of microprocessor as CPU, semiconductor memories like EPROM and RAM, input device, output device and interfacing devices. The memories, input device, output device and interfacing devices are called peripherals. The popular input devices are keyboard and floppy disk and the output devices are printer, LED/LCD displays, CRT monitor, etc.

CPU

ALU

Input

CU

Output

Memory

CPU-> Central Processing Unit ALU -> Arithmetic and Logical Unit CU -> Control Unit Block Diagram of a computer with the Microprocessor as CPU

Microprocessor based system

Processor System ArchitectureThe typical processor system consists of: CPU (central processing unit) ALU (arithmetic-logic unit) Control Logic Registers, etc Memory Input / Output interfaces Interconnections between these units: Address Bus Data Bus Control Bus

Bus and CPUBus: A shared group of wires used for communicating signals among devices. address bus: the device and the location within the device that is being accessed, unidirectional data bus: the data value being communicated, bidirectional control bus: describes the action on the address and data buses; like Reset the device CPU: Core of the processor, where instructions are executed High-level language: a = b + c Assembly language: add r1 r2 r3 Machine language: 0001001010111010101

Central Processing UnitMicroprocessor consists of ALU, REGISTER ARRAY and CONTROL UNIT. ALU (Arithmetic and Logical Unit): Computing functions are performed on data in this area of microprocessor. It performs arithmetic and logic operations. REGISTER ARRAY: It is a group of various registers. They are used to store data temporarily during the execution of a program. CONTROL UNIT: It controls the flow of data between the microprocessor and peripherals (I/0 ports and memory) by sending proper timing and control signals.

Memory and I/O Memory: Where instructions (programs) and data are stored. stores binary information, called instructions and data. provides the instructions and data to the microprocessor on request. stores results and data for the microprocessor. I/O devices: Enable system to interact with the world. Device interface (a.k.a. controller or adapter) hardware connects actual device to bus The CPU views the I/O device registers just like memory that can be accessed over the bus. However, I/O registers are connected to external wires, device control logic, etc. The I/P device enters data and instructions under the control of a program such as a monitor program. The O/P device accepts data from the microprocessor as specified in a program.

Computer classificationComputers are divided into three categories as per the superiority and number of microprocessors used. These are: A microcomputer is a small computer containing only a single central processing unit (CPU). Their word length varies between 8 and 32 bits and used in small industrial and process control systems. The storage capacity and speed requirements of microcomputers are moderate. Mini computers are having more storage capacity and more speed than micro computers. Mini computers are used in research, data processing, scientific calculations etc. Mainframe computers are designed to work at very high speed and they have very high storage capacity. Their word length is typically 64-bits. These are used for research, data processing, graphic applications, etc.

Advantages of Microprocessor based system Computational/processing speed is high. Intelligence has been brought to systems. Automation of industrial processes and office administration. Since the devices are programmable, there is flexibility to alter the system by changing the software alone. Less number of components, compact in size and cost less. Also it is more reliable. Operation and maintenance are easier.

Disadvantages of Microprocessor based System It has limitations on the size of data. The applications are limited by the physical address space. The analog signals cannot be processed directly and digitizing the analog signals introduces errors. The speed of execution is slow and so real time applications are not possible. Most of the microprocessors does not support floating point operations.

Microcontrollers Integration of Microprocessor along with I/O ports and minimum memory in a single package is named as microcontroller. Peripherals like programmable timer is also included in a single package. Sometimes microcontroller is called single chip micro-computer.ROM/RAM Memory Micro Processor I/O Ports

Peripheral Timer

Digital Signal Processors A Digital Signal Processor is a special-purpose CPU (Central Processing Unit) that provides ultrafast instruction sequences, such as shift and add, and multiply and add, which are commonly used in math-intensive signal processing applications. A digital signal processor (DSP) is a specialized microprocessor designed specifically for digital signal processing, generally in real time. Digital operati