1. EMBEDDED SYSTEM
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 hardware 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.

2. 8051 MICROCONTROLLER
PORT1
PORT0
PORT3
PORT2

3. I.S.P. I.S.P refers to In system programming .
Vcc
RXD
TXD
PSEN
RST
1kΩ
2 x 33pF
MHz
I.S.P.
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

4. Vcc
RXD
TXD
PSEN
RST
1kΩ
2 x 33pF
MHz

5. 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.

6. 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.

7. 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.

8. 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 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).