An embedded system is a special-purpose computer system and a combination of software and hardware designed to perform specific task. It is usually a complete device including It is usually a complete device including hardware and mechanical partshardware and mechanical parts It is different from a general-purpose computer, such as a personal computer, which can do many different tasks depending on programming but the embedded system is dedicated to specific tasks.

PORT0PORT1

PORT2

PORT3

Vcc

RXD

TXD

PSEN

Vcc

RST

RXDTXD

PSEN1kΩ

2 x 33pF

11.0592MHz

I.S.P refers to In system programming .

It is a circuit arrangement in which we can program and reprogram the microcontroller without removing it from the circuit in which it is being used

Vcc

RXD

TXD

PSEN

Vcc

RST

RXDTXD

PSEN1kΩ

2 x 33pF

11.0592MHz

Examples of embedded systerms embedded systems range from portable

devices such as digital watches and MP4 players.

large stationary installations like traffic lights, factory controllers;

the systems controlling nuclear power plants etc.

MICROCONTROLLERS A microcontroller is a small computer on a

single integrated circuit consisting of a relatively simple CPU combined with some support functions.

Program memory in the form of flash memory or ROM is often included on chip, as well as a, typically small, read/write memory.

Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, remote controls, office machines, appliances, power tools, and toys.

8051Microcontroller The 8051 microcontroller is 8 Bit

microcontroller and one of the most popular general purpose microcontrollers in use today.

The Intel 8051 is an 8-bit microcontroller which means that most available operations are limited to 8 bits.

There are 3 basic "sizes" of the 8051 Short, Standard, and Extended.

FEATURES OF 8051 It provides many functions (CPU, RAM, ROM, I/O,

interrupt logic, timer, etc.) in a single package it is an 8-bit microcontroller. On-chip RAM - 128 bytes(data memory) On-chip ROM - 4 kiB (program memory) Four byte bi-directional input/output port Two 16-bit Counter/timers (usually 2, but may

have more, or less). Four 8-bit ports, (short models have two 8-bit

ports).