In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values—typically, the values being in the midst of a calculation at a given point in time. Most, but not all, modern computer architectures operate on the principle of moving data from main memory into registers, operating on them, then moving the result back into main memory—a so-called load-store architecture. Computer architecture is the theory behind the design of a computer. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article is about the computer architecture. ...

Processor registers are the top of the memory hierarchy, and are the fastest way for the system to manipulate data. Registers are normally measured by the number of bits they can hold, for example, an "8-bit register" or a "32-bit register". Registers are now usually implemented as a register file, but they have also been implemented using individual flip-flops, high speed core memory, thin film memory, and other ways in various machines. The hierarchical arrangement of storage in current computer architectures is called the memory hierarchy. ... This article is about the unit of information. ... 8-bit refers to the number of bits used in the data bus of a computer. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... A register file is an array of processor registers in a central processing unit (CPU). ... This article is about the electronic component. ... A 16×16 cm area core memory plane of 128×128 bits, i. ... Thin film memory is a high-speed variation of core memory developed by Sperry Rand in a government-funded research project. ...

The term is often used to refer only to the group of registers that can be directly indexed for input or output of an instruction, as defined by the instruction set. More properly, these are called the "architected registers". For instance, the x86 instruction set defines a set of eight 32-bit registers, but a CPU that implements the x86 instruction set will contain many more registers than just these eight. An instruction set, or instruction set architecture (ISA), describes the aspects of a computer architecture visible to a programmer, including the native datatypes, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O (if any). ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

There are several other classes of registers:

• Data registers are used to store integer numbers (see also Floating Point Registers, below). In some simple/older CPUs, a special data register is the accumulator, used for arithmetic calculations.
• Address registers hold memory addresses and are used to access memory. In some simple/older CPUs, a special address register is the index register (one or more of these may be present)
• General Purpose registers (GPRs) can store both data and addresses, i.e., they are combined Data/Address registers.
• Floating Point registers (FPRs) are used to store floating point numbers.
• Constant registers hold read-only values (e.g., zero, one, pi, ...).
• Vector registers hold data for vector processing done by SIMD instructions (Single Instruction, Multiple Data).
• Special Purpose registers store internal CPU data, like the program counter (aka instruction pointer), stack pointer, and status register (aka processor status word).
  • Instruction registers store the instruction currently being executed.
  • Index registers are used for modifying operand addresses during the run of a program.
• In some architectures, model-specific registers (also called machine-specific registers) store data and settings related to the processor itself. Because their meanings are attached to the design of a specific processor, they cannot be expected to remain standard between processor generations.
• Registers related to fetching information from random access memory (a collection of storage registers located on separate chips from the CPU):
  • Memory buffer register
  • Memory data register
  • Memory address register

Hardware registers are similar, but occur outside CPUs. In computer science, the term integer is used to refer to any data type which can represent some subset of the mathematical integers. ... In a CPU, an accumulator is a register in which intermediate results are stored. ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ... An index register in a computer CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/array operations. ... A floating-point number is a digital representation for a number in a certain subset of the rational numbers, and is often used to approximate an arbitrary real number on a computer. ... A vector processor, or array processor, is a CPU design that is able to run mathematical operations on a large number of data elements very quickly. ... In computing, SIMD (Single Instruction, Multiple Data) is a set of operations for efficiently handling large quantities of data in parallel, as in a vector processor or array processor. ... The program counter (also called the instruction pointer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence. ... A stack is a data structure that works on the principle of Last In First Out (LIFO). ... A status register is a collection of flag bits for a microprocessor that indicates the status of various mathematical operations. ... In computing, an instruction register is the part of a CPUs control unit that stores an instruction. ... In mathematics, an operand is one of the inputs of an operator. ... Look up RAM and random access memory in Wiktionary, the free dictionary Different types of RAM. From top to bottom: DIP, SIPP, SIMM 30 pin, SIMM 72 pin, DIMM, DDR DIMM Random access memory (sometimes random-access memory), commonly known by its acronym RAM, is a type of computer storage... The Memory Buffer Register (MBR) in the central processor that stores the data being transferred to and from the immediate access store. ... The memory data register is the register of a computers control unit that contains the contents of a register to fetch or store from or to the computer storage. ... The memory address register is the register of a computers control unit that contains the address of a register to fetch or store from or to the computer storage. ... In computing, a hardware register is a storage area for hardware I/O (input/output) of different kinds. ...