The dirty little secret in the computer world is that even though you're buying a processor with four cores, all four of those cores might not actually be used when you're running applications. Most software today is still single-threaded, which means the program is running as one process and a process can only run on one core.
So even if you have four cores, you won't be getting the full performance of all four cores for that application. That's why you also need to check the single-threaded or single-core performance of any processor before buying it. Not all companies explicitly release that information, so you'll need to rely on third-party data from reliable resources like Passmark benchmark tests. The cache is one of the most under-appreciated parts of a CPU. In fact, a cache with poor specs could be slowing down your PC!
So always check the cache specs of a processor before you purchase it. Cache is essentially RAM for your processor , which means that the processor uses the cache to store all of the functions it has recently performed. Whenever those functions are requested again, the processor can draw the data from the cache instead of performing it a second time, thus being faster.
Processors have different levels of cache, starting with L1 and going up to L3 or L4, and you should only compare cache size at the same level. New processors can usually handle the graphics requirements of most everyday users without requiring a separate graphics card.
These graphics chipsets also vary in performance depending on the processor. Again, you can't compare an AMD to an Intel here, and even comparing within the same family can be confusing. In short, graphics processing on CPUs is still quite confusing, but you still need to pay attention to it! A chip is also called an integrated circuit. Generally it is a small, thin piece of silicon onto which the transistors making up the microprocessor have been etched.
A chip might be as large as an inch on a side and can contain tens of millions of transistors. Simpler models might consist of a few thousand transistors etched onto a chip just a few millimeters square. It has become common to see chips in all kinds of devices with multiple cores, each of which is a processor.
To understand how a microprocessor works, it is helpful to look inside and learn about the logic used to create one. In the process you can also learn about assembly language — the native language of a microprocessor — and many of the things that engineers can do to boost the speed of a processor. A microprocessor executes a collection of machine instructions that tell the processor what to do.
Based on the instructions, a microprocessor does three basic things:. There may be very sophisticated things that a microprocessor does, but those are its three basic activities. The following diagram shows an extremely simple microprocessor capable of doing those three things:. Although they are not shown in this diagram, there would be control lines from the instruction decoder that would:.
Coming into the instruction decoder are the bits from the test register and the clock line, as well as the bits from the instruction register. The previous section talked about the address and data buses, as well as the RD and WR lines. In our sample microprocessor, we have an address bus 8 bits wide and a data bus 8 bits wide. That means that the microprocessor can address bytes of memory, and it can read or write 8 bits of the memory at a time. Let's assume that this simple microprocessor has bytes of ROM starting at address 0 and bytes of RAM starting at address ROM stands for read-only memory.
A ROM chip is programmed with a permanent collection of pre-set bytes. The address bus tells the ROM chip which byte to get and place on the data bus. RAM stands for random-access memory. RAM contains bytes of information, and the microprocessor can read or write to those bytes depending on whether the RD or WR line is signaled. One problem with today's RAM chips is that they forget everything once the power goes off.
That is why the computer needs ROM. By the way, nearly all computers contain some amount of ROM it is possible to create a simple computer that contains no RAM — many microcontrollers do this by placing a handful of RAM bytes on the processor chip itself — but generally impossible to create one that contains no ROM.
When the microprocessor starts, it begins executing instructions it finds in the BIOS. The BIOS instructions do things like test the hardware in the machine, and then it goes to the hard disk to fetch the boot sector see How Hard Disks Work for details. The microprocessor then begins executing the boot sector's instructions from RAM. The boot sector program will tell the microprocessor to fetch something else from the hard disk into RAM, which the microprocessor then executes, and so on.
This is how the microprocessor loads and executes the entire operating system. Even the incredibly simple microprocessor shown in the previous example has a fairly large set of instructions that it can perform. The collection of instructions is implemented as bit patterns, each one of which has a different meaning when loaded into the instruction register.
Humans are not particularly good at remembering bit patterns, so a set of short words are defined to represent the different bit patterns. This collection of words is called the assembly language of the processor. An assembler can translate the words into their bit patterns very easily, and then the output of the assembler is placed in memory for the microprocessor to execute.
Here's the set of assembly language instructions that the designer might create for the simple microprocessor in our example:. Eight of those wires represent individual bits. Since binary code is really just representation of whether or not power is on or off, we can represent an eight bit binary instruction by applying or not applying power to eight of the nine wires.
So we've sent an instruction to our imaginary processor by applying electricity or not on eight of the processor's wires that represent eight bits of data. Now it's time to pull the crank, so to speak. To do so, the computer would apply power to the processor's ninth wire. This would let the computer know that the instruction is complete and that it can be acted on. The processor's ninth wire, would be connected to the computer clock. Every time the clock ticks, power would be applied to this wire.
If the clock ticked once per second, then the processor would be able to process one instruction per second.
It isn't that data can't be sent to the processor any faster, but the clock has to keep everything in sync. Without the clock, the processor has no way of knowing where one instruction ends and the next one begins.
As I said earlier though, this example is grossly oversimplified. Today's processors can handle bit instruction sets, and clock speeds are measured in gigahertz. A gigahert is roughly equivalent to a billion clock cycles per second.
Earlier I mentioned that clock speeds are not as important today as they once were. Today, clock speeds represent the number of instruction sets that can be processed each second, just as has always been the case. The problem is that as clock speeds began to approach 4 GHz. Generally speaking, the higher the clock speed, the more heat the processor is going to produce.
Currently, the lack of a low-cost heat dissipation mechanism is preventing Intel and AMD from mass marketing CPUs with higher clock speeds. This seems to have put an end to the clock speed wars have gone on for so long. Rather than focusing on higher clock speeds, both Intel and AMD have turned their focus toward doing more with existing clock cycles. The reason why clock speeds are less important than they once were is because newer processor designs can allow multiple instruction sets to be processed with each clock cycle.
For example, a 2 GHz processor that processes two instruction sets per clock cycle could potentially be faster than a 3 GHz processor that processes one instruction set per clock cycle. I say could potentially be, because it really depends on the chip architecture and on the operating system and applications that are being run.
Processing multiple instruction sets per clock cycle almost always means running parallel threads. Unless you are running multithreaded application on an operating system that is designed to simultaneously run multiple threads, you will see no real benefit processing multiple instruction sets in a single clock cycle.
I will talk about multiple threads in a lot more detail later on in another article. Another factor that greatly affects a processor's performance is the processor's cache. The processor's cache has absolutely nothing to do with the speed at which the processor runs at least not in terms of clock speed. However, it greatly affects the system's overall performance.
The basic idea behind the CPU cache is that the cache consists of a small amount of very expensive, but very fast memory. This memory is integrated onto the CPU. Probably the best analogy that I've heard to describe how a CPU cache works is to compare it to the way that a library works.
When it comes to discussing microprocessors, their function, and more, you're likely to come across a number of terms that you may not be familiar with. The following are some common terms related to microprocessors:.
Word length refers to the number of bits in the processor's internal data bus--or the number of bits that a processor can process at any given time. For example, an 8-bit processor will have 8-bit registers, an 8-bit data bus, and will perform 8-bit processing at a time.
The instruction set is the series of commands that a microprocessor can understand. Essentially, it's the interface between the hardware and the software. The cache memory is used to store data or instructions that the software or program frequently references during operation.
Basically, it helps to increase the operation's overall speed by allowing the processor to access data more quickly than from a regular RAM. The clock speed is the speed at which a microprocessor is able to execute instructions. A bus is the term used to describe the set of conductors that transmit data or that address or control information to the microprocessor's different elements.
Most microprocessors consist of three different buses, which include the data bus, the address bus, and the control bus. Microprocessors can be based on the number of bits the processor's internal data bus or the number of bits that it can process at a time which is known as the word length. Based on its word length, a microprocessor can be classified as 8-bit, bit, bit, and bit.
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