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Computing Systems

EC4012PAPIC 18F4520

Chapter 1

Introduction

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What is a Computer?

Processor Input Devices Output Devices Memory Devices

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Processor

A processor is also called the central processing unit (CPU).

The processor consists of at least the following 3 components:• A register • Arithmetic logic unit (ALU). • Control unit.

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Microprocessor

is a processor in a single ic chip a microcomputer is a computer that

uses a micro-processor as its CPU. is referred to as 4-bit, 8-bit, 16-bit, 32-

bit, or 64-bit. word length of the microprocessor.

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Microprocessor

is not designed to deal with I/O. interface chips are needed. External memory chips are needed to

hold programs and data Glue logic is required to interface with

the memory chips, Peripheral chips are needed to interface

with I/0 devices.6

What is a Microcontroller ?

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CPU

Memory

I/O, Serial, Parallel Ports

Timer/CounterUART

ADC, DACDMA

Block Diagram of a Microcontroller

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Control Bus

CPU ALU

Control

Register

Address Bus

Memory

RAM

[Data]

I/O

Output Device

sInput

Devices

Clock

ROM

[Program]

StackData Bus

Common characteristics of Microcontroller

“Embedded” inside the products we use everyday.

“Dedicated” to one task / one specific program

Designed for “low-cost, small, low-power performance”.

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MCU

What is a Microcontroller use for ?

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Microcontroller is Everywhere

Consumer Market – includes home appliances:

washing machines, TV remotes, MP3 players, VCR and refrigerator

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Microcontroller is Everywhere

Automotive market

remote keyless entry, antilock braking and air bags

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Microcontroller is Everywhere

Office automation

PCs, keyboards, mouse, modem, sound card, copiers, scanner and printers

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Microcontroller is Everywhere

Telecommunications

cellular phones, PSPs, pagers and answering machines

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Microcontroller is Everywhere

Industrial products

door locks in hotel rooms, battery chargers and industrial machinery

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Memory

Programs and data are stored in memory in a computer.

A computer may contain: semiconductor ; magnetic (harddisk); and optical (cdrom, DVD).

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Memory

Semiconductor memory can be further classified into two major types: random access memory (RAM) and read-only memory (ROM).

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RAM

Volatile - cannot retain data in the absence of power.

also called read write memory. Reading memory is nondestructive. Writes data will overwrite the old

data.

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RAM

Two types of RAM technology: static RAM (SRAM) and dynamic RAM (DRAM).

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ROM

Read_Only memory is non-volatile , it retain data in the absence of power.

Data stored in these chips is either unchangeable or requires a special operation to

change. 20

Thank You

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