A 25MHz 80486 SX processor. Not very fast but it's not the slowest 486 ever made. This one runs 5MHz faster which is noticeably in applications. The SX25 could be overclocked to 33MHz quite often without any hassle. 8MHz may not sound much but will greatly improve the speed of the system. Especially as the front-side-bus (FSB) goes up to 33MHz as well. In case the system is equipped with a Vesa Local Bus (VLB) graphics card the VLB bus goes up to 33MHz as well. In my opinion this is quite an ideal situation for a PC as the processor can ship it's data to the rest of the system as fast as possible because everything runs at the same speed.
The 486 had several improvements over the 386DX. Except for the SX versions it featured an internal co-processor. Both the SX and DX versions had internal cache, branch prediction and a five-stage pipeline. The internal cache (8KB) functions as a buffer for small data. Because the cache is inside the processor it can be accessed with higher speeds compared to the normal RAM. With branch prediction the processor will think in advance and get everything ready for the coming instructions. Pipelining is something that every modern CPU uses. See it as extinguishing a fire: without pipelining you have to fill a bucket of water, walk to the fire and dispose the water. With pipelining one fill the bucket, gives the bucket to the person standing next to him, he gives it to the person next to him and he gives it to the one that throws the water on the fire. This method of working will speed up the processor.
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