The Apple III was released by Apple Compute in 1980 as a business computer. It was the successor to the Apple II but failed to deliver. It featured a full 80-column display, a full-stroke keyboard with upper and lower case, ran on a Synertek 6502B processor at 1.8MHz and had 128KByte of RAM on board, upgradeable to 512KByte.

Because the Apple III failed to sell in large numbers, Apple reconsidered the plans to retire the Apple II, and instead took some of the features of the Apple III and incorporated them into later models of the Apple II

The 6502 is an 8-bit MicroProcessor designed by MOS Technology. The team was led by Chuck Peddle and had also worked on the Motorola 6800. The 6502 is a simplified, but faster and cheaper design than the 6800.

The 6502 was introduced in 1975 and was the cheapest microprocessor on the market. Together with the Zilog Z80, the 6502 helped start the home computer revolution of the 1980s. The 6502 was used in a wide range of devices: the Atari 2600, the 8-bit Atari home computers, the Apple II, the Nintendo Entertainment System, the Commodore 64, the BBC Micro and many others. All used the 6502 or a variation of it.

The 6502 is a 1MHz design, while the 6502A is designed for 2MHz. The 6502A is 100% compatible with the original 6502.

Commodore soon bought MOS Technology, but conitnued to sell the microprocessor to competitors and licensed the design to other manufacturers.