Microprocessor

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 and, its , and its. Processors are also often classified as either RISC or CISC based on their instruction set complexity.

History
The first commercial microprocessor was the Intel which appeared in 1971. This was the CPU member of a set of four integrated circuits called the, 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.

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).

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

Early era

 * Apple I: 1 MHz, 8-bit MOS 6502
 * Apple III: 1.8 MHz, 8-bit Synertek SY6502
 * Apple II GS : 2.8 MHz, 8/16-bit WDC 65C816

68k CISC era

 * Apple Lisa: 5 MHz, 16/24-bit Motorola 68000
 * Macintosh 128K: 7.8336 MHz, 16/24-bit Motorola 68000
 * Macintosh II: 16 MHz, 32-bit Motorola 68020
 * Macintosh Quadra 700: 25 MHz, 32-bit Motorola 68040

PowerPC RISC era

 * Power Macintosh 6100: 60 MHz - 66 MHz, 32-bit PowerPC 601
 * Power Macintosh 6400: 180 MHz - 200 MHz, 32-bit PowerPC 603e
 * iMac G3: 233 MHz - 700 MHz, 32-bit PowerPC G3
 * Power Mac G4: 350 MHz PowerPC G4 – 1.42 GHz, 32-bit PowerPC G4 (2x)
 * Power Mac G5: 1.6 GHz PowerPC G5 – 2.5 GHz, 64-bit PowerPC G5 (4 cores)

Intel era

 * Mac mini: Intel Core Solo (1 core) – Core i7 (6 cores)
 * MacBook Pro: Intel Core Duo (2 cores) – Core i9 (8 cores)
 * Mac Pro: Intel Xeon (4 to 28 cores)

Apple Silicon era

 * Mac mini: 3.2 GHz Apple M1
 * MacBook Pro 14/16-inch: 3.22 GHz Apple M1 Pro or M1 Max
 * Mac Studio: 3.22 GHz Apple M1 Max or M1 Ultra
 * MacBook Air: 3.49 GHz Apple M2