Difference between Microprocessor and Microcontroller

Parameter	Microprocessor	Micro controller
Description	It is Multipurpose, Programmable device that accepts digital data as input from external input unit, processes it as per instructions in its memory, and provides results as output at external output unit.	It is a Self Contained System with a processor core, memory, and peripherals and can be used as embedded system.
Software Protection	Software Protection is less achieved in Microprocessor based systems.	Micro controllers offer more software protection by locking the on chip memory and is made protected from external circuit.
Input/output Devices	Keyboard, Mouse, Screen, disks, printers etc.	Switches, Relays, LEDs, LCD Displays, radio Frequency devices ,Sensors
Cost	High, Because Devices like memory, disks, and interfaces are connected externally and has to be purchased separately.	Decreased net cost of the embedded system as a whole, Because no needs to

Difference between Single and Multiprocessor Systems

Parameter	Single Processor Systems	Multiprocessor Systems
Description	If a System contains only one processor for processing than it is called single processor system.	If a System contains two or more than two processors for processing than it is called multiprocessor system.
Use of Co-Processors	Yes, Single Processors uses multiple Controllers that are designed to handle special tasks and can execute limited instruction sets. E.g. DMA Controller, North/South Bridge.	In Multi Processor Systems Two Types of approaches are Used: 1)      Symmetric Multiprocessing(SMP) 2)      Asymmetric Multiprocessing In Asymmetric Multiprocessing one Processor works as Master and Second Processor act as Slave And in Symmetric Multiprocessing each processor performs all the tasks within the operating system.
Throughput	Throughput of Single Processor Systems is less than Multiprocessor Systems Because each and every task is performed by the same processor.	Throughput of Multiprocessor systems is greater than single processor systems. If a System Contains N Processors

Overclocking

Operating a Chip at higher clock speed than its rated clock speed is called Overclocking. CPU Clock speed is the product of FSB (Front Side Bus) Clock and clock multiplier. Overclocking is achieved by either increasing FSB Clock or Clock multiplier or either by increasing both.

Need of Overclocking

The idea behind the use of Overclocking concept is to increase the system performance at no cost or very little cost. We can Overclock a processor by just changing some settings on motherboard or in CMOS setup. The main considerable point in Overclocking is heat. Processor can only be overclocked if and only if proper cooling is there. E.g. Pentium 4 @2.0 GHz Processor can be overclocked to gain 2.2 GHz Clock speed.

Is it Risky?