Processor register & l1 cache question??

ChadaeChadae Member Posts: 65 ■■□□□□□□□□
Im a lil bit shaky on this topic. Im studying from my a+ cert bible and need to understand this...The use of a (processor) register is basically to store data and to be able to retrieve this data quicker...then the l1 cache memory is "memory" stored in the processor itself. So whats the difference between these two icon_confused.gif: I dont get it. Why even have a register built in some processors??


  • ChadaeChadae Member Posts: 65 ■■□□□□□□□□
    Gee, I guess nobody knows... icon_confused.gif:
  • Ricka182Ricka182 Member Posts: 3,359
    The caches are essentially very fast memory. They store frequently used, or most likely to be used information so that the CPU will not have to always go to the slower main memory for it. The size, speed and organization of the caches has a major effect on CPU performance. The L1 cache is the fastest and most expensive and thus the smallest. As part of the CPU, it runs at the CPU speed and it's the first place the CPU looks. If the desired information is not in L1, the CPU will check the L2 cache, which is somewhat slower, but still faster than main memory (4-5.5ns). The L2 cache started its life on the system board and because the CPU communicated with it over the FSB, its speed was tied to the FSB's. Starting with the PII, Intel has moved the L2 cache on the processor card itself, where it runs at half the CPU speed.

    As we shall see, other subsystems are extremely slow relative to the processor subsystem. For example video memory reads are about 7-8MB/sec and disk transfer rates are about 12-15MB/sec. This is why, depending on your applications and how you run them, a faster CPU will not necessarily increase overall performance.

    Hope that helps. Correct me if I'm wrong.
    i remain, he who remains to be....
  • ChadaeChadae Member Posts: 65 ■■□□□□□□□□
    Thanks again ricka182! That seemed to clear things up a bit. I think from searching online i found out too that the Register processes as well as stores information. It also gives a processor quicker access to data.

    So I guess the register and the cache memory pretty much do the same thing.
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