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Apple Wiki

A microprocessor is a computer whose entire central processing unit (CPU) is contained on one (or a small number of) integrated circuits. The important characteristics of a microprocessor are the widths of its internal and external address bus and data bus, its clock rate, and its instruction set. Processors are also often classified as either RISC or CISC based on their instruction set complexity.[1]


The first commercial microprocessor was the Intel 4004 which appeared in 1971. This was the CPU member of a set of four LSI integrated circuits called the MCS-4, which was originally designed for use in a calculator but was marketed as "programmable controller for logic replacement". The 4004 is referred to as a 4-bit microprocessor since it processed only 4 bits of data at a time. This very short word size is due mainly to the limitations imposed by the maximum integrated circuit density then achievable.[1]

As integrated circuit densities increased with the rapid development of integrated circuit manufacturing technology, the power and performance of the microprocessors also increased. This was reflected in the increase in the CPU word size from 4 to 8, 16, and 32 bits by the mid 1980s. Early microprocessors had relatively simple instruction sets with no floating-point instructions, sometimes requiring a separate floating-point unit (FPU).[1]

Microprocessors in Apple products[]

A list of microprocessors and clock rates of selected Apple products:

Early era[]

68k CISC era[]

PowerPC RISC era[]

Intel era[]

Apple Silicon era[]


See also[]

External links[]

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