Docstoc

Characteristics of a Central Processing Unit (CPU)

Document Sample
Characteristics of a Central Processing Unit (CPU) Powered By Docstoc
					**RG**

Central Processing Unit (CPU) is the component of the computer running the computer
programs. With memory in particular, it is one of the components that have existed
since the first computers, a processor built into a single integrated circuit is a
microprocessor.

The processors were designed from the beginning specifically for a computer of a given
type. This expensive method of processor design for a specific application has led to the
development of mass production of processors that are suitable for one or more uses.

This standardization trend that started in mainframes (discrete transistor mainframes
and minicomputers) has accelerated rapidly with the advent of integrated circuits.
Integrated circuits have enabled the miniaturization of processors. The miniaturization
and standardization of CPUs have contributed to their dissemination in modern life far
beyond the uses of programmable machines.

While the complexity, size, construction, and the general form of CPUs have changed
considerably over the last sixty years, the design and basic function has not changed
much. Almost all common CPUs today can be described very precisely as machines of
von Neumann's stored program.

Composition of a processor

The essential parts of a processor are:

    * Arithmetic Logic Unit (ALU), which supports basic arithmetic calculations and
tests;
    * The control unit or sequencer, which synchronizes the various components of the
processor. In particular, it initializes the registers when you start the machine and it
handles interruptions;
    * Records, which are memories of small (few bytes), fast enough that the ALU can
manipulate the content at each clock cycle. A number of records are common to most
processors:
           - Meter: This register contains the memory address of the instruction being
executed;
           - Accumulator: This register is used to store data being processed by the
ALU;
           - Address register: it always contains the address of the next information to be
read by the ALU, that is between the current instruction or the next instruction;
           - instruction register: contains the instruction being processed;

Register state: it is used to store the context of the processor, which means that
different bits of this register are the flags for storing information regarding the outcome
of the last instruction executed;
           - stack pointers: this type of register, whose number varies depending on the
processor type, contains the address of the stack(s);
          - general registers: These registers are available for calculations;
    * Clock that synchronizes all actions of the CPU. It is present in the processors,
synchronous and asynchronous absent processors and processors Autosynchronous;
    * The unit input / output, which supports communication with the memory of the
computer or the transmission of orders for its fly specialized processors, allowing the
processor to access devices on the computer.

				
DOCUMENT INFO
Shared By:
Tags:
Stats:
views:12
posted:1/11/2013
language:
pages:2