A microprocessor is an implementation of physical CPUs in a single integrated circuit.
Microprocessors are used in many digital devices.
Depending on their use are divided into categories:
General-purpose, are the microprocessors used in personal computers. They have high performance and very flexible.
Special-purpose, they are microprocessors that have specific tasks. They are found in video cards.
Embedded are microprocessors that are designed solely to run a single application.
In addition to the processors in a processing system is a hierarchical memory system and a set of I / O, which can interconnect other systems or other devices.
For each system can be made different classifications depending on the parameters used:
-Computing power (scientific)
-Power graphics (games)
Tansazioni-operated unit of time (database)
Another key aspect is the reliability of the system.
Performance and reliability
Depending on the characteristics of microprocessors have very different prices. For the price of microprocessor embedded systems is very limited, since they usually have to play a few keystrokes and a low speed.Microprocessors for desktop systems will have enough content pricing based on performance in computing speed. For servers, however, have very high costs depending on their speed and reliability, since the non-operation of the system for a given period of time, may cause a great loss of money (in particular the cost of a malfunction is calculated as fault detection time + repair time).
The main parameters for determining the speed of a processor are:
-Throughput, which indicates the amount of operations performed in a given period of time.
-Latency, which indicates the average execution time of a transaction.
Another important factor, especially for mobile devices is power consumption.
The CPU is not the only parameter to be taken into consideration for assessing the possibility of a microprocessor system, since the performance depends also and above all by:
-Architecture System (BUS, organization of memory, I / O. ..)
-Performance peripherals (network, storage devices ...)
Software-based management (multithreading ...)
-Management of peripheral (DMA / Interrupt, interrupt levels ...)
When building server is not the biggest cost is given by the microprocessor, but the memories. In fact, in a system-oriented web applications, 40% of the time is spent executing instructions, while a full 60% is done to perform I / O: if you replace the processor with a 10 times faster than it has an increase in performance (speed up) of about one and a half.
Another critical aspect of modern systems is the dissipated power, both at the processor, both of the microprocessor.In fact about 70% of energy used by a normal desktop PC is used for cooling.
Multicore processors are trying to work at a lower frequency (to reduce the power dissipation), allowing the computing power equal.
Components of microprocessors
A microprocessor is composed of several parts, some of them are:
-ALU (Algebrical Logic Unit).
-Unit decodes the instructions (check the schedule forfetch, decode and execute).
Unit-address management (transforms logical addressesinto real addresses)
-Register (store the data on which to perform the operations)
BUS-Management Unit (who is to rule the command of the BUS)