The Apple III Plus was a result of the discontinuation of the Apple III. The Apple III was in violation of FCC regulations, and the FCCC demanded the company change the name of the redesigned computer, to avoid any confusion.

The Apple III Plus has a built-in clock, video interlacing, standardized connections, 256KByte RAM and a redesigned keyboard that was more like the Apple IIe. Owners of the Apple III could purchase individual III+ upgrades such as the clock, and get a service replacement of hte new logic board. Apple also provided a keyboard upgrade kit, which had to be installed by an authorized technician.

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.