MOS Technology 6502 | 1975
MOS Technology 6502
The 6502 is an 8-bit microprocessor released by MOS Technology in 1975. It was used in a variety of electronic devices such as the Apple I, Commodore 64, Nintendo Famicom, and Atari 2600. Known for its low cost and excellent performance, the 6502 was widely adopted in many electronic products and had a significant impact on the computer and gaming industries.
The development of the 6502 was led by Chuck Peddle and engineers who had previously worked at Motorola. The Motorola 6800 microprocessor was too expensive, and in order to make it more affordable, Peddle and his team moved to MOS Technology and developed the 6501. However, due to the similarities between the 6501 and the 6800, Motorola filed a lawsuit, and the 6501 was withdrawn from sale. After modifying the pin configuration and improving certain functions, the 6502 was released and quickly became popular in a wide range of devices.
The 6502 has a total of six 8-bit registers (A, X, Y, P, S) and a 16-bit program counter (PC). While the number of registers was limited, the processor supported a variety of addressing modes, allowing for efficient memory usage. The 6502 was made with approximately 3,000 transistors, making it much smaller than processors of its time, and its low cost contributed to its widespread adoption.
The 6502 supported 13 different addressing modes, which allowed it to efficiently access memory and registers. For example, the "Accumulator" mode uses the A register as the operand, and the "Absolute" mode directly specifies a memory address for the operation.
