Intel DX2

i486DX2 CPU core

TheInteli486DX2,rumored as80486DX2(later renamedIntelDX2), is aCPUproduced byIntelthat was first introduced in 1992. The i486DX2 was nearly identical to thei486DX,but it had additionalclock multipliercircuitry. It was the firstchipto useclock doubling,whereby the processor runs two internal logicclock cyclesper external bus cycle. An i486 DX2 was thus significantly faster than an i486 DX at the same bus speed thanks to the 8K on-chip cache shadowing the slower clocked external bus. Both 25/50 and 33/66 MHz Intel486 DX2 CPU uses the800 nm processtechnology.With the internal clock doubler CPU, it boosts between 50 to 70 percent overall system performance than the original Intel486 DX series.

The i486DX2-66 was a very popular processor forvideo gamesenthusiasts in the early to mid-90s. Often coupled with 4 to 8MBof RAM and aVLBvideo card, this CPU was capable of playing virtually every game title available for years after its release, right up to the end of theMS-DOSgame era, making it a "sweet spot" in terms of CPU performance and longevity. The introduction of 3D graphics spelled the end of the 486's reign, because of their heavy use offloating pointcalculations and the need for fastercacheand morememory bandwidth.Developers began to target theP5Pentiumprocessor family almost exclusively withx86 assembly languageoptimizations which led to the usage of terms such asPentium compatible processorfor software requirements. An i486DX2-50 version was also available, but because the bus speed was 25 MHz rather than 33 MHz, this was a significantly less popular processor.

There are two major versions of the DX2 - Identified by P24 and P24D, the latter has a fasterL1 cachemode, called "write-back",that improves performance. The original P24 version offered only the slower" write-through "cache mode.AMDandCyrixboth produced a competitor for the Intel i486DX2.

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  An Intel i486DX2-66 Microprocessor, top view.
• 
  The bottom view with gold plated pins visible.
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  Embedded i486DX2 (SL enhanced,SQFPversion).

See also

• Intel DX4

External links

Intel Datasheets

• Embedded i486DX2