A register is a small, high-speed storage memory within the central processing unit (CPU) or the arithmetic logic unit (ALU). Registers are used for temporary storage of data that requires immediate processing during arithmetic and logic operations. They are essential in computer systems for enhancing CPU performance and efficiency by enabling fast access to frequently used data and facilitating efficient data manipulation.
A computer program’s register allocation is either done by a compiler during code generation or manually by an assembly language programmer. The number of available registers, their size and capacity and the types of operations they can perform have a major impact on program execution speed. Registers are used to store data, control signals and other information that is frequently accessed during computer processing. They provide fast access to data, eliminating the need for frequent trips to slower primary memory. In addition, storing frequently used values in registers allows for parallel and speculative execution.
The term “register” is also used to refer to a list or record, particularly a legal document or other official record, that details information such as names, birth dates, addresses, and financial transactions. A common example is a property deed register in which a local government-generally at the county, town or state level-maintains a record of all real estate deeds.
In computing, a register is a type of variable-sized, high-speed memory used in the central processing unit (CPU) or arithmetic logic unit (ALU). These registers are essential to a computer’s operation because they enable rapid access to frequently used data and facilitate efficient data manipulation.
There are a variety of different types of registers, each with its own purpose and usage. Most are divided into data registers and address registers; the latter may be combined into general-purpose registers in some architectures. Data registers can hold numeric data values, typically integers but sometimes floating-point numbers in some processors; they may also contain characters and small bit arrays. Address registers contain addresses for memory locations, used by instructions that indirectly access primary memory.
A special class of registers called status or truth value registers holds truth values, typically used to indicate the results of instruction execution. Specialized floating-point registers can be used to handle the higher arithmetic precision needed by certain functions. A few processors have special function registers that correspond to specialized hardware elements such as vector coprocessors or floating-point math units. The registers themselves are normally implemented as flip-flops, which require more hardware than simple memory cells and increase the cost of a processor. As a result, the number and type of registers in a CPU determines its overall cost. Despite the higher cost, many processors use multiple registers to optimize performance. This is known as pipelined execution, a technique that reduces memory access times and improves CPU efficiency. A similar technology is used in microcontrollers, where special registers can be added to a simple IC to add functionality such as timers and counters.