 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 faster L1 cache mode, called "write-back", that improves performance.The original P24 version offered only the slower "write-through" cache mode.