Processor registers are the main assistants

The processor belongs to the number of software-controlled devices and is intended for information processing. The information is processed in accordance with a predefined program. Actually, this process looks like this: when you run the program is placed in the RAM, and from there one command after another goes to the processor. In addition to the commands for computation, you also need data that can come from both RAM and external devices.

As a result of the execution of the next command, the result is obtained, which must be saved somewhere. And then there are two options - to send the result to RAM or leave it inside the processor, since, most likely, this result is inconclusive and will be used in further calculations. In the first case, there is one big "BUT" - for such exchanges with memory, a considerable amount of time is spent, and, consequently, system performance is reduced. In the second case, the processor must contain in its structure memory elements called processor registers. These are devices that serve to receive, store and transmit a multi-bit binary data code . Registers of the processor are divided into two types: general-purpose registers and specialized registers.

Registers of the general-purpose processor serve to store the intermediate results of the calculations. The more such registers inside the processor, the less often it refers to RAM, that is, it does not spend time on it and, therefore, does not lose in performance. But on the other hand the number of registers is limited by the area of the processor chip. Infinitely increase their number can not. Registers intended for data storage, as a rule, have a bit width equal to the width of the data bus. Each processor register has its own unique name, by means of which you can access the register through the program code.

Each of the specialized registers has its own special purpose. For example, there is a register for storing the address of the command in the RAM, which must be read at the next access. This register is called the register of the address of the command. Another example of a specialized register is the register of characteristics. In another way, it is also called the word processor state (Processor Status Word - abbreviated PSW). Unlike all other registers of the processor, the contents of which are considered entirely, each bit of the register of characteristics has a unique name and a separate purpose. Among the characteristics for the example can be identified so-called sign of zero (a sign of zero result). If as a result of execution of any command the result is zero, then the processor can "learn" about this by analyzing this bit of the register of characteristics.

The processor registers are very fast memory (even faster than the cache memory), because they are in the immediate vicinity of the processing core and run on the clock frequency of the internal bus of the processor.