Intel 80486DX2

The Intel 80486DX2 is a CPU produced by Intel that was introduced in 1992. The 80486DX2 is identical to a 80486DX but with one difference. It was the first chip to use "clock doubling" technology, whereby the processor performs two clock cycles per single cycle of the memory bus. Essentially, the processor's speed is set to double of the speed of the system bus. Because of this, an Intel 80486DX2 is slower than an Intel 80486DX-based system at the same processor speed; a normal DX chip performs one processor clock cycle per system bus cycle (is aligned to the same speed as the system's bus).

Intel produced two 80486DX2 CPUs:

• 50 MHz CPU for systems with a 25 MHz front side bus
• 66 MHz CPU for systems with a 33 MHz front side bus

AMD also produced an 80MHz 'DX2' chip for systems with a 40MHz front side bus.

It is now standard practice for a CPU to perform more than one clock cycle per bus clock cycle.