One of several different Caches available today. It works by directly mapping certain blocks of memory to one certain block of cache. For instance block 1010010 in memory will always be mapped to block 0010 in the cache, no matter what. That way if you want to look for 1010010 in cache you know exactly where it should be. If it's not there then you know you've just wasted your time and to go to memory.

    One thing to know about how direct-mapped cache is that the location a memory block is mapped to directly depends on its least signifigant bits. So any memory block with the least signifigant bits "0010" will, if its in cache, be in location "0010" in the cache. The most signifigant bits of the memory block are actually stored in the cache itself for reference.

    Of course once a momory block is loaded and it has the same cache location as an old block, the old block is erased and the new put in. You can't store two at once. Also the locations dont have to be 8 bits long, as I used above, I was just using those as an example.

    So now that you have this useless knowledge of how this cache works what do you do with it? I don't know. Go fix the ozone layer problem or something.