<P> This led to modern random - access memory (RAM). It is small - sized, light, but quite expensive at the same time . (The particular types of RAM used for primary storage are also volatile, i.e. they lose the information when not powered). </P> <P> As shown in the diagram, traditionally there are two more sub-layers of the primary storage, besides main large - capacity RAM: </P> <Ul> <Li> Processor registers are located inside the processor . Each register typically holds a word of data (often 32 or 64 bits). CPU instructions instruct the arithmetic logic unit to perform various calculations or other operations on this data (or with the help of it). Registers are the fastest of all forms of computer data storage . </Li> <Li> Processor cache is an intermediate stage between ultra-fast registers and much slower main memory . It was introduced solely to improve the performance of computers . Most actively used information in the main memory is just duplicated in the cache memory, which is faster, but of much lesser capacity . On the other hand, main memory is much slower, but has a much greater storage capacity than processor registers . Multi-level hierarchical cache setup is also commonly used--primary cache being smallest, fastest and located inside the processor; secondary cache being somewhat larger and slower . </Li> </Ul> <Li> Processor registers are located inside the processor . Each register typically holds a word of data (often 32 or 64 bits). CPU instructions instruct the arithmetic logic unit to perform various calculations or other operations on this data (or with the help of it). Registers are the fastest of all forms of computer data storage . </Li>

An example of an internal memory strategy is