Virtual or logical memory is a concept that, when implemented by a computer and its operating system, allows programmers to use a very large range of memory or storage addresses for stored data. The computing system maps the programmer’s virtual addresses to real hardware storage addresses. In addition to managing the mapping of virtual storage addresses to real storage addresses, a computer implementing virtual memory or storage also manages storage swapping between active storage (RAM) and hard disk or other high volume storage devices. Data is read in units called “pages” of sizes ranging from a thousand bytes (actually 1,024 decimal bytes) up to several megabyes in size.
Cache ram is very high-speed RAM chips which sit between the CPU and main memory. It stores memory accesses by the CPU. Cache ram helps to alleviate the gap between the speed of a CPU’s megahertz rating and the ability of RAM to respond and deliver data. It reduces the frequency that the CPU must wait for data from the main memory.