It was the outcome of an idea proposed by Ted Hoff of Intel Corp. The first microprocessor, the four-chip set Intel 4004, appeared in 1971 accompanied by considerable debate about its utility and marketability. Instructions generally include arithmetic, logical, flow-of-control, and data movement (between stacks, registers, memory, and I/O ports). Note that a word is usually defined as the number of bits in the processor' internal data bus rather than always being 16 bits. The data types, which are the fundamental entities that can be manipulated by the instruction set, have included bit, nibble (4 bits), byte (8 bits), word (16 bits), double words (32 bits), and quadruple words (64 bits). The processor' architecture determines what register, stack, addressing, and I/O facilities are available, as well as defining the processor' primitive data types. RISC microprocessors are designed to execute a small number of simple instructions extremely fast. Microprogrammed processors have a control store containing the microcode or firmware that defines the processor' instruction set such processors may either be implemented on a single chip or constructed using bit-slice architecture elements. Most microprocessors have a fixed instruction set. It is the combination of these characteristics and not just the cycle time that determines the performance of a microprocessor. They are characterized by speed, word length (internal and external), architecture, and instruction set, which may be either fixed or microprogrammed. Microprocessors consist of, at a minimum, an ALU and a control unit. A semiconductor chip, or chip set, that implements the central processor of a computer.

All generation of microprocessor