In computing, an instruction register is the part of a CPU's control unit that stores the instruction currently being executed. In simple processors each instruction to be executed is loaded into the instruction register which holds it while it is decoded, prepared and ultimately executed, which can take several steps. More complicated processors use a pipeline of instruction registers where each stage of the pipeline does part of the decoding, preparation or execution and then passes it to the next stage for its step. Modern processors can even do some of the steps of out of order as decoding on several instructions is done in parallel. Originally, the word computing was synonymous with counting and calculating, and a science and technology that deals with the original sense of computing mathematical calculations. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... A control unit is the part of a CPU or other device that directs its operation. ... An instruction pipeline is a technique used in the design of microprocessors and other digital electronic devices to increase their performance. ...

Decoding the opcode in the instruction register includes determining the instruction, determining where its operands are in memory, retrieving the operands from memory, allocating processor resources to execute the command (in superscalar processors), etc. Microprocessors perform operations using binary bits (on/off/1or0). ... Simple superscalar pipeline. ...