Introduction to Micro processor Microprocessor instruction and opcodes Mnemonics

OBJECTIVES Understand what a microprocessor is, what it does, and

how it works. Understand the concepts of RAM and ROM computer

memory and how memory is accessed via the address and data buses.

Understand how parallel and serial data interfaces work. Perform relevant calculations pertaining to analog-to-

digital converters and digital-to-analog converters. Understand the principles of digital controller software. Recognize and describe the characteristics of the various

types of available digital controllers, that is, microcontrollers, single-board computers, programmable logic controllers, and personal computers.

Microprocessors ushered in a whole new era for control systems electronics.

Microprocessors require additional components to be useful – RAM, ROM, etc.

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A computer is made up of four basic blocks:◦ Central Processing Unit (CPU)

Does the actual computing. Arithmetic Unit – performs math and

logic Control: Manages flow of data

◦ Memory – Data is contained in memory locations at specified addresses. RAM – volatile, read/write memory ROM – nonvolatile, read only EPROM/EEPROM/Flash – Erasable ROM

Input/Output ports: Used for connections to devices.

Busing:◦ Devices are multiplexed using 3 major buses:

Address Bus – To specify the device or memory location to communicate with.

Data Bus – To transfer data between the CPU and device.

Control Bus – Timing and event control, such as read and write operations.

Each processor has its own instruction set of commands to control its operation.◦ Move data◦ Perform math operations◦ Perform logical operations

Each instruction has a unique Op-code, a binary value associated to it.01001101 or 4Dh.

An Accumulator is staging area for data – data is moved into it, and operations are performed on that data.

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Machine Code◦ The program the CPU follows represented in binary or hex.

Mnemonics ◦ Abbreviations representing an op-code. Programs written

in assembly language use mnemonics. Program counter

◦ Used to point to the memory address of the instruction to be performed.

Fetch-execute cycles◦ Performed to bring an instruction into memory and execute

it.

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