mikroinstruction

A mikroinstruction is a low-level instruction that is part of a computer's control unit's microprogram. Microinstructions are the fundamental building blocks of how a processor executes machine code instructions. When a processor fetches a machine code instruction, the control unit interprets this instruction and generates a sequence of mikroinstructions. These mikroinstructions then control the flow of data and the operation of the processor's components, such as the arithmetic logic unit (ALU), registers, and memory.

Each mikroinstruction typically specifies a set of operations to be performed simultaneously. These operations might include selecting ALU functions, moving data between registers, or enabling/disabling memory access. The sequence of mikroinstructions for a given machine code instruction is stored in a special memory called the control store or microprogram memory. This microprogram acts as an interpreter, translating complex machine instructions into simpler, elementary steps.

The concept of microprogramming was introduced by Maurice Wilkes in 1951. It allows for greater flexibility in processor design, as the instruction set can be modified or extended by changing the microprogram without altering the hardware. Complex instructions can be implemented as a series of simpler mikroinstructions, making the hardware design simpler and more modular. This approach also facilitates the emulation of different instruction set architectures on the same hardware. Mikroinstructions are not directly executed by the programmer but are an internal mechanism of the processor.