The Tangerine Microtan 65 was a 6502 based single-board micro computer, first sold in 1979. The design became the basis for the Oric ATMOS computer and its successors.

The Microtan 65 has a single step function that can be used for debugging at the hardware level. The computer was available as a kit, or as a pre-built unit. The kit required soldering the parts on the motherboard.

The major advantage of the Microtan 65 was flicker free video. Computers like the ZX81 would turn off the display on a keystroke, since the CPU handled video by software and could only perform one task. The Microtan's processor, the 6502 has a regular period in each instruction cycle when all CPU activity is inside the chip, leaving the external memory available for other things like video display. The same technique is also used on the Oric-1 and the Atmos. The Apple II Computer also used this feature of the 6502

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.