Microcontroller

Comparison between micro-controller and microprocessor

Sr No.	Microcontroller	Microprocessor
1.	Inbuilt RAM or ROM	Do not have inbuilt RAM or ROM
2.	Inbuilt Timer	Do not have inbuilt Timer
3.	I/O ports are available	I/o ports are not available ,requires extra device like 8155 or 8255.
4.	Inbuilt serial port	Do not have inbuilt serial port , requires extra devices like 8250 or 8251
5.	Separate memory to store program and data	Program and data are stored in same memory
6.	Few instructions to read or write data to or from external memory.	Many instructions to read or write data from or to external memory.

A microcontroller is an entire computer manufactured on a single chip. Microcontrollers are usually dedicated  devices embeded within an application
Example microcontrollers are used as engine controllers in engine automobiles and as exposure and focus controllers in cameras .

Features of 8051:-

• 8 bit bus and 8 bit ALU.
• 16 bit address bus  -64 KB of RAM and ROM.
• On-chip RAM 128(256 ) bytes (Data Memory) and On Chip ROM -4 KB (Program memory)
• Four 8 -bit bi directional input /output ports.
• Programmable serial ports i.e. One UART(serial port).
• Power saving mode.
• All modern versions are CMOS.