80486DX2/66

A processor made by Intel in the early 90's. Was extremely fast for its days. It was essentially a 486 chip that ran at twice the speed of its external bus. You could therefore plug an 80486DX2/66 into a motherboard that used to have an 80486DX/33 in it, and your computer would feel twice as fast. There was also an 80486DX2/50, but it sucked compared to an 80486DX/50, which ran natively at 50Mhz.
Clock multiplying is now a way of life in the computer industry.

In the UK, at least, the 486DX2/66 was the aspirational computer of choice just as 'Doom' was being released, and could run the game and its sequel without slowing down on the more complex levels. A lot of people switched allegiance from the Commodore Amiga or Atari ST because of this, and the DX2/66 was the first PC to really take off in the domestic market; a DX2/66 running Windows 3.11 was the face of the IBM PC in the UK from 1993 to 1996. It remained the entry-level right up until the advent of the Pentiums, as many people avoided the subsequent DX4/100 for fear of instant obsolesence.

In November 1994, a 484DX2/66, with 16 meg RAM, a 810 meg hard drive, a 2X cd-rom drive, a Diamond Stealth 64 and a 15" VGA monitor would have set you back somewhere in the region of £1,800. Today such a machine would be unsaleable, although still useful for word-processing and browsing the internet, especially so if one avoids Flash-heavy sites.

At the time the DX2/66 overshadowed the DX/50, a machine which, due to the tricky clock-doubling used by the DX2, was actually slightly faster.