Computer Processor and its Internal Components
Processor Internal Components
In any computer system, the most essential component is the processor or the CPU (Central Processing Unit), which is also commonly referred to as the microprocessor. The Computer Processor processes information and interfaces with many other system elements to retrieve data to be processed and return the data that has been processed.
Generally, the processor performs the following functions in a computer system:-
- Fetches, decodes and executes instructions obtained from software programs
- Performs arithmetic calculations
- Controls and supports the timing of each operation
The speed of the computer processor is a major factor in determining the performance of the PC, that is, how fast instructions will be executed.
An AMD Processor
The CPU is also one of the most expensive components on the motherboard. It is a very delicate device and sensitive to ESD, thus it should be handled with care. The processor itself is a flat plate of silicon made up of millions of transistors etched on to the silicon plate to form a huge computer logic circuit.
A ceramic cover is placed over the micro-circuit to protect it and to conduct heat away to the heat sink. This protective ceramic covering will have print information of the processor type, speed, and other details.
Though Intel is the best known company in processor manufacturing, we have a wide range of processors from other manufacturers such as:
- Advanced Micro Devices (AMD)
- Integrated Device Technology (IDT) - acquired by VIA
Each of these companies offer competitively priced processor chips with comparable performance to Intel processors. They also offer compatibility with Microsoft operating system software. In terms of processor technology advancement, these other manufacturers are also not left behind.
How the Processor Operates
The computer processor fetches, decodes, and executes program instructions. A computer program consists of a series of steps called instructions which tell the computer what to do. Each instruction can be a basic arithmetic calculation or a logic operation. Before the program can be executed it is loaded into the working space (memory).
It is the job of the microprocessor, which is controlling the computer to fetch a program instruction from the memory, decode the instruction and then carry out any action that might be needed which is the execution process. It is the responsibility of the processor inside the computer to carry out the fetch-decode-execute cycle over and over again operating from the instructions it obtains from the main memory.
This fetch - decode - execute cycle is often referred to as the fetch - execute cycle.
The CPU uses a timing signal to be able to fetch and execute instructions. The timing signal is provided by the system clock. The clock speed is measured in Hz (cycles per second). In early processors speed was measured in Megahertz (MHz) is one million hertz (1 million cycles per second). Most of the computers we have today operate in the GHZ (Gigahertz) range. The clock speed varies from one computer processor to another.
Key Components Found Inside a Processor (CPU)
Arithmetic and Logic Unit (ALU)
This is the brain of the microprocessor. The ALU performs basic arithmetic calculations like adding, subtracting, multiplication and division of figures, it also performs logical operations like comparison of figures.
Control Unit (CU)
As the name suggests, this component controls all the functions that take place inside the processor itself. It instructs the ALU on which arithmetic and logical operation is to be performed. It acts under the direction of the system clock and sorts out all the internal data paths inside the processor to make sure that data gets from the right place and goes to the right place.
Register also sometimes known as the accumulator, is a temporary storage position where data coming from RAM heading to the processor for execution and data coming from the processor after processing is held. Thus a register is a local storage area within the processor that is used to hold data that is being worked on by the processor.
Internal Registers (Internal Data Bus)
This is the bus connecting the internal components of the processor to the motherboard. The size of the internal registers indicates how much information the processor can operate on at one time and how it moves data around internally within the chip. This is sometimes also referred to as the internal data bus. A register is a holding cell within the processor; for instance, the processor can add numbers in two different registers, storing the result in a third register. The register size determines the size of data on which the processor can operate.
External Data Path
This is the path (bus) used to fetch data from memory to the processor. In some cases the internal and external data buses are the same bit-size but in others, the external data bus can be either narrower or wider. The external data path is normally not as wide as the internal data path.
Having a smaller external bus (data path) will slow the performance of the-CPU, but it makes it simpler to upgrade earlier system designs to a new processor. Having a larger external data bus will improve the performance as data can be brought into the CPU in large chunks.
The address lines are used to specify the exact location in memory where data can be found. The standard PC is a binary device. Using the memory address bus, CPUs send out location information on their address lines (or control lines) and these address lines are routed to every other major component of the computer (memory, ROM, expansion bus etc).
The numbers of address lines within the memory address bus will determine the maximum number of addressable locations. For example, if a PC has 3 address lines the maximum number of addressable memory locations is 8.
Whenever you are using a computer to achieve a task, the computer processor gets busy fetching, decoding and executing program instructions that are being issued to it. But remember it must work in conjunction with other computer components so as to achieve the desired goals.
© 2011 Patrick Kamau
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