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Internal random access memory (RAM) is computer memory that is built directly into the chip of a microcontroller, such as a computer’s central processing unit (CPU). It can be used by programmers to increase the speed of program functions by directly addressing internal RAM, ensuring that critical processes are queued and processed faster and at higher priority by the CPU. This can greatly speed up processor-intensive applications because frequently used instructions can be passed to the CPU much faster than drawing them from external ram.
CPUs have three levels of cache, or internal RAM. Processor cache is comprised of static RAM (SRAM), which is not the same as the typical memory installed on the motherboard, called dynamic RAM (DRAM). When the CPU looks for data, it checks first the Level 1 (L1) cache, then Level 2 (L2), then Level 3 (L3). Only after that will it pull data from the DRAM.
Within the processor, L1 cache is assigned to every core on the processor itself. This is the fastest internal RAM, because it acts as the buffer for instructions handed to each processor core as dictated by the program requesting processing. In multi-core processors, this can substantially speed processing if multiple cores are addressed individually through L1 cache requests.
The L2 cache is in the CPU package and thus is still considered internal RAM. It is not built directly onto the actual CPU chip as L1 cache is. Each core still has its own L2 cache dedicated to it and thus can operate in parallel, taking advantage of the L2 speeds. L2 cache is slower than L1 cache, however.
L3 cache is not within the CPU package, so it is not considered internal RAM but instead functions alongside it. It is the fastest external RAM available within a computer. All CPU cores share the L3 cache.
The entire process can be viewed as a queueing and breaking down of data from external DRAM, to internal RAM and finally to the actual processing instructions. Certain functions within any program are established at a higher priority than others, and those are moved to the front of the queue as part of the individual program’s optimization. The highest priority data is addressed directly to L1 cache for fastest processing, and the lowest priority queues through the entire process. The main difference is where cache is processed in a “pull from the waiting queue” method, internal RAM is software addressable, so data can be specifically assigned to individual internal RAM levels.