One of the most important parts of a computer is the central processing unit or CPU. This is the component that makes all computations possible, and performs four basic logical operations that complete the fetch-decode-execute cycle of a computer. Regardless of its brand or type every new CPU contains millions of transistors, which are its building blocks that work by amplifying or switching an electronic signal. Each transistor has a base, emitter, and collector and putting a few transistors together forms a logic gate, gates are used to create binary code and give the CPUs their processing powers. The transistor-based processors are far superior to their predecessors since they operate at much higher speed, offer superb reliability, and lower power consumption.

Each modern CPU contains a number of important elements, which are listed below, along with a short description:

Execution Core(s)

Refers to the number of execution cores that are found in a single chip. The most sophisticated CPUs have eight execution cores, which allow them to handle far more applications.

Data Bus

A subsystem that allows information to be transferred within the CPU and from the CPU to other components in the computer – the higher the speed of the bus, the faster the data will be transferred.

Address Bus

A set of lines that determines where in the main memory will the data be transferred and the number of lines determines the amount of memory that can be accessed directly.

Math Co-processor

A computer chip that performs some of the mathematical computations (typically floating-point functions) and thus frees the main processor. While in the past the co-processor was a separate physical processor in the computers today it is typically built into the CPU.

Instruction sets / Microcode

Translates the machine instructions into circuit-level operations and what makes the control logic of the computers possible.

Multimedia extensions (or MMX)

Additional set of instructions that come built-in into an Intel Pentium chip and improve performance.

Registers

The CPUs own memory locations that are accessed much quicker than the external memory.

Flags

Used in microprocessors to show or control the outcome of an operation.

Pipelining

The connection of the different CPU elements, which allows the output of one element to become the input of the next one.

Memory Controller

A separate chip that controls the flow of data to and from the main memory.

Cache Memory (L1, L2 and L3)

A high-speed, static RAM the CPU can access much faster than the computer RAM. The L1 level is the fastest and the smallest in capacity and the one that the CPU tries to access first, while the L3 is the slowest and the biggest. Each of the elements (L1, L2, and L3) is accessed in succession by the CPUs before an attempt is made to access the RAM and the advantage of multi-level caches is that the time for accessing the memory is greatly reduced.

Measuring the speed of a processor is typically done by measuring its clock cycles, bits, and execution cores. The number of bits a CPU can process in a single instruction is important because a higher bit CPU can work with larger numbers and compute smaller numbers faster. Even though the 64-bit computers have been around since the early 1970s, they have only recently entered the PC arena. Another important factor of a CPU is its clock rate, which is measured in hertz. Clock rate should be used to compare only processors of the same type, and is not the only component that determines the processor’s speed. When it comes to execution cores, more cores allow a microprocessor to handle greater number of applications quickly and efficiently.

There are many CPU manufacturers today, but the two that are considered leaders in this segment of the industry and are fighting a head-on battle for the consumer’s dollar are Intel and AMD. However, even after a few very successful years for AMD, their processors still hold only 12% of the global processor’s market, while Intel has managed to capture more than 80%. While the AMD processors have always been cheaper than the Intel ones and are typically more efficient, the Intel CPUs are often faster; however, since both companies manufacture various microprocessors any general comparison is probably superfluous. The fierce competition between the two computer giants (and the long court battle) has resulted in great technological developments, and in 2010, both companies have announced their six-core desktop processors.

It should be noted that the central processing unit does not work in isolation and other factors contribute greatly to the computer’s performance – if you are on the market for a new machine, take into consideration its RAM, graphic card, and hard disk as well.