Introduction
The processors (or CPU, Central Processing Unit – Central Processing Unit) are chips responsible for the implementation calculations, logical decisions and instructions that result in all the tasks that a computer can do. For this reason, are also referred to as the “brains” these machines.
Although there may not be a very large number of manufacturers – the largest part of the market is concentrated in the hands of the Intel and AMD, with companies such as Samsung and Qualcomm stood out in mobile -, there is a wide variety of processors, for the most varied purposes.
In spite of the differences between each model, most of the chips share certain characteristics.Based on this, the AbbreviationFinder displays this text input to the processors, where you will come to know the meaning concepts such as clock, bit internal, cache memory, use of two or more cores, etc.
What is the processor?
The processor (CPU) is a chip usually made of silicon which responds by the execution of the duties applicable to a computer. For to understand how a processor works, it is convenient to divide a computer in three parts: processor, memory, and a set input devices and output (or I/O, Input/Output). In this last, is if any item is responsible for input or output of data in the computer, such as screens, keyboards, mice, printers, scanners, hard disks, etc. In this scheme, the processor exercises the function main, already that’s up to him access to and the use of the memory and input and output devices to the running of the activities.
To better understand, suppose you want your computer run a program (software). In a few words, a program consists of in a series of instructions that the processor must execute to that the requested task is performed. For this, the CPU transfers all of the data necessary for the execution of a device input and/or output – such as a hard disk – for the memory. From there, all the work it is done and what will be done of the result depends on the purpose program – the processor can be instructed to send the information obtained to the HD again, or to a printer, for example.
Buses
The image below illustrates a hypothetical layout (and quite abstract) communication between the processor, the memory and the set of devices input and output, representing the basic operation of the computer. Note that the connection between these items is indicated by arrows. This is done so that you can understand the function of buses (bus).
In general, the buses are responsible by the interconnection and communication of devices on a computer. Note that, for the processor to communicate with memory and the set of input and output devices, there are three arrows, that is, buses: one is the bus address (address bus); the other, data bus (data bus); the third, a control bus (control bus).
The bus address, basically, indicates where the data to be processed should be removed or to where they should be sent. Communication through this medium is one-way, the reason why there is only arrow on one end the line on the chart which represents your communication.
As the name makes clear, is by the data bus that the information it is in transit. In turn, the control bus is the synchronization of such activities, by enabling or disabling the flow of data, for example.
For you to understand better, imagine that the processor needs of a given present in the memory. By the bus address, the CPU retrieves the location of this data within the memory. As only need to access the data, the processor indicates by bus control that this is a read operation. The data is then located and inserted in the data bus, where the processor finally reads it.
Internal Clock
In a computer, all of the activities require synchronization. The internal clock (or just clock) serves precisely this purpose, that is, basically, acts as a signal for timing. When the devices of the the computer receive the signal to perform their activities, the this event in the name of “pulse clock”. On each pulse, the devices perform their tasks, stop and go to the next clock cycle.
The measurement of the clock is made in hertz (Hz), the standard unit of measures of frequency, which indicates the number of oscillations or cycles that occur within a certain measure of time, in this case, seconds. Thus, if a processor works at 800 Hz, for example, means that it is capable of dealing with 800 operations in clock cycles per second.
Note that, for practical purposes, the word kilohertz (KHz) is used to indicate 1000 Hz, as well as the term megahertz (MHz) is used to refer to 1000 KHz (or 1 million hertz). In the same way, gigahertz(GHz) is the name used when you have 1000 MHz, and so on. With this, if a processor account with, for example, a frequency of 800 MHz, this means that can work with 800 million cycles per second.
At this point, you should probably have understood that it is from here that comes expressions such as “processor Intel Core i5 2.8 GHz”, for example.
Front Side Bus (FSB)
You already know: the frequency with which the processors work are known as internal clock. But, the processors also come with what is called external clock or Front Side Bus (FSB) or, still, front-side bus.
The FSB exists because, due to physical limitations, the processors can communicate with the chipset and the RAM memory – more precisely, with the memory controller, which can be in the north bridge (northbridge) chipset – using the same speed of the internal clock. Thus, when this communication is made, the external clock frequency more low, is that it comes in.
Note that, to obtain the internal clock, the processor makes use of a procedure multiplication of the external clock. To better understand, suppose that a particular processor has external clock of 100 MHz. As your manufacturer indicates that this chip works at 1.6 GHz (or is, has internal clock of 1.6 GHz), your external clock is multiplied for 16: 100 x 16 = 1600 MHz or 1.6 GHz.
It is important to make it clear, however, that if two processors different – one from Intel and another of AMD, for example – have internal clocks that of the same value – 3,2 GHz, for example -does not mean that they both work with the same speed. Each processor has a project distinct and has characteristics that determine how fast can be. Thus, a given processor can lead to for example, 2 clock cycles to execute an instruction. In another processor, this same statement may apply 3 cycles.
It’s also worth mentioning that many processors – especially the latest – transfers 2 or more data per clock cycle, giving to understand a chip that performs, for example, transfer 2 data cycle-by-cycle and is working with external clock of 133 MHz, makes the 266 MHz processor. For this and other reasons, it is a mistake to consider only the internal clock as a parameter of comparison between processors different.
QuickPath Interconnect (QPI) and HyperTransport
Depending on the processor, another technology can be used in place of the FSB. An example is the QuickPath Interconnect (QPI), used on newer chip from Intel, and the HyperTransport, applied on CPUs from AMD.
These changes of technologies are required because, with the passing of time, the search for better performance causes the processors suffer changes considerable in its architecture.
One of those changes pertains to the already mentioned memory controller circuit, responsible for”mediate” the use of memory RAM by the processor. In CPUs most current Intel and AMD, the driver is integrated into the the chip itself and not the chipset located on the motherboard.
With this integration, the processors now have a bus direct memory access. The QPI and HyperTransport end up then getting free to do the communication with the resources that are still intermediated by the chipset, such as input and output devices.
The interesting thing is that both the QuickPath and the HyperTransport work with two-way communication, so that the processor can transmit and receive data at the same time, as each activity is targeted to a via, benefiting from the aspect of performance. In FSB this does not happens, because there is only a single route for the communication.
