clock rate ” Clock speeds  “ is the speed at which a microprocessor executes instructions. every computer contains an electronic clock, which produces a sequence of regular electrical pulses used by the control unit to synchronize the components of the computer and regulate the fetch-execute cycle by which program instructions are processed that regulates the rate at which instructions are executed and synchronizes all the various computer components. The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second.

in other word ,  clock rate is the fundamental rate in cycles per second at which a computer performs its most basic operations such as adding two numbers or transferring a value from one processor register to another. it is the frequency of the clock in any synchronous circuit.

Clock speeds are expressed in megahertz – millions of pulses a second – (MHz)  or gigahertz (GHz).

Centrino it is not a CPU ,  the Centrino term covers a particular combination of mainboard chipset, mobile CPU and wireless network interface in the design of a laptop produced by Intel so naming it Centrino platform is more appropriate . Intel claimed that systems equipped with these technologies should deliver better performance, longer battery life and broad wireless network interoperability.

We mean here central processing unit (CPU) is an mechanical cog that can execute computer programs. Modern microprocessors appear in everything from automobiles to cell phones to children toys.

The fundamental operation of most CPUs, regardless of the physical form they take, is to execute a sequence of stored instructions called a program. The program is represented by a series of numbers that are kept in some kind of computer memory. There are four steps that nearly all CPUs use in their operation: fetch, decode, execute, and writeback.

fetch: involves retrieving an instruction (which is represented by a number or sequence of numbers) from program memory.

decode : the instruction is broken up into parts that have significance to other portions of the CPU .

execute : various portions of the CPU are connected so they can perform the desired operation. If, for instance, an addition operation was requested, an arithmetic logic unit (ALU) will be connected to a set of inputs and a set of outputs.

writeback : writes back the results of the execute step to some form of memory .