What purpose do registers serve within the CPU?

Answer 1

Well, if your question is also "Why do we need registers?" then my answer would be that it quickens the mathamatical process of buying goods or services. If cashiers were good enough, and fast enough at math, there really wouldn't be a need.

Answer 2

Registers are an important part of any microprocessor or microcontroller. For any instruction to be executed, certain data has to be present and available so that the executions can be performed.

For example, adding two numbers requires the two numbers at 'hand.' This is where the registers come into picture. The two numbers to be added are saved on some registers. These are the memory that are available directly to the Arithmetic logic unit. So data (or memory location addresses) is directly read from these registers (accumulator A, B, C, D; generally) and the results are also saved on them, or the memory location pointed by them.

Answer 3

A register is the lowest level of data storage in a computer. Registers also have the lowest read/write time of all types of memory in your computer, making them idea to perform small, repeated calculations.

Of course, each CPU has a limited number of registers, so they can only be used for very short term data storage while that data is being processed.

=====================================================================

Registers are areas of the CPU onto which data is loaded at the start or end of the computational processes undertaken by the CPU.

Answer 4

Registers are temporary storage areas in the CPU to use for doing work. Nearly everything you do with CPU instructions involve registers. Here are some of the types of registers and their purpose:

General purpose registers - The majority of instructions involve general purpose registers. They are used for loading things into the CPU from memory and for writing to memory. They are used for arithmetic and logical operations. If you add, subtract, multiply, divide, compare, rotate, shift, etc., you are doing it to registers.

Instruction Pointer - This is not a user accessible register, but it is necessary since it keeps track of where the CPU is executing instructions.

Segment Registers - These registers are used for addressing memory. In real mode, they are necessary for specifying which chunk of memory you need to access. Real mode used 64k blocks of memory, so you had to tell it which 64k block to work with. In protected or virtual mode, they are used as selectors, and they are mostly off-limits to programmers while in those modes.

Flags Register - This is a register that contains the status flags for the various operations, and also denotes the CPU type and any error conditions. So if the result of a mathematical calculation overflows, is a negative number, if the result is equal, if carrying needs to be done, etc., this is where all that is recorded. If you do conditional jumps ("jump if equal," for instance), those instructions will look at the flags register to see if the execution needs to jump to the specified location. Conditional jumps are a bit like using IF, THEN, and GOTO together in BASIC, and the flags register makes them possible.

Stack Pointer - The system stack is a location of memory that is used for temporary storage. The PUSH instruction saves a general purpose register to the stack so the register can be freed up and used for something else, while maintaining what was there. The POP instruction moves the data back from the stack to a general purpose register. Each time something is copied to the stack the stack pointer moves down an address location. Each time something is copied from the stack, the stack pointer moves upward an address. The stack pointer determines where to read or write the stack data. In Real mode, the stack segment pointer is also used to determine the block of memory in which the stack pointer works.

Answer 5

They provide the processor a quick area to store small amounts of information to use later on as relying on RAM or permanent storage may be much slower.

Answer 6

to hold the data for execution unit